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These are answers that matrix has provided in Chemistry

Question/Answer
cheriskae asked on 01/31/08 - help

Using chemical test, how can you distinguish among 2-pentanone,3-pentanone and pentanal?
Can you also draw the structure of a compound, C5H8O that gives a positive iodoform test and does not decolorize permanganate?

matrix answered on 02/01/08:

Hello cheriskae

In the future please one problem per question.
..................................................................
(1)Using chemical test, how can you distinguish among 2-pentanone,3-pentanone and pentanal?
...

Only pentanal will give a positive Tollens test and only 2-pentanone will give a positive iodoform test.
...
Tollens reagent (silver mirror test) is used as a test for aldehydes, which are oxidized to carboxylic acids.
...
The iodoform test is a qualitative chemical test for the detection of ketones and aldehydes carrying an alpha methyl group. Alcohols with groups such CH3CH(OH)-R will also give positive test.
...
3-Pentanone will negative results in both of these tests.
....................................................................
(2) Can you also draw the structure of a compound, C5H8O that gives a positive iodoform test and does not decolorize permanganate?

...
Permanganate decoloration is used as a qualitative test for the presence of an alkene (Bayer test).
...
For C5H8O the only material that contains a methyl ketone and no unsaturation is cyclopropyl methyl ketone.
...
See webpage below for structure.
http://orgsyn.org/orgsyn/orgsyn/prepContent.asp?prep=cv4p0597

cheriskae rated this answer Excellent or Above Average Answer

Question/Answer
cheriskae asked on 01/31/08 - help

Using chemical test, how can you distinguish among 2-pentanone,3-pentanone and pentanal?
Can you also draw the structure of a compound, C5H8O that gives a positive iodoform test and does not decolorize permanganate?

matrix answered on 02/01/08:

Hello cheriskae

In the future please one problem per question.
..................................................................
(1)Using chemical test, how can you distinguish among 2-pentanone,3-pentanone and pentanal?
...

Only pentanal will give a positive Tollens test and only 2-pentanone will give a positive iodoform test.
...
Tollens reagent (silver mirror test) is used as a test for aldehydes, which are oxidized to carboxylic acids.
...
The iodoform test is a qualitative chemical test for the detection of ketones and aldehydes carrying an alpha methyl group. Alcohols with groups such CH3CH(OH)-R will also give positive test.
...
3-Pentanone will negative results in both of these tests.
....................................................................
(2) Can you also draw the structure of a compound, C5H8O that gives a positive iodoform test and does not decolorize permanganate?

...
Permanganate decoloration is used as a qualitative test for the presence of an alkene (Bayer test).
...
For C5H8O the only material that contains a methyl ketone and no unsaturation is cyclopropyl methyl ketone.
...
See webpage below for structure.
http://orgsyn.org/orgsyn/orgsyn/prepContent.asp?prep=cv4p0597

cheriskae rated this answer Excellent or Above Average Answer

Question/Answer
cheriskae asked on 01/25/08 - Please help

Instead of t-butyl alcohol, what other compounds can we use to form1,4-di-t-butyl-2,5-dimethoxybenzene?

matrix answered on 01/27/08:

In Friedel Crafts reaction there are 3 common kinds of reactants.
1) Alcohols
2) Bromo or chloro compounds. In your case you would use tert-butyl chloride or tert-butyl bromide.
3) Alkenes. In this case you would use isobutylene.

cheriskae rated this answer Excellent or Above Average Answer

Question/Answer
cheriskae asked on 01/24/08 - help me out please

Why is the 1,4 isomer, 1,4-di-t-butyl-2,5-dimethoxybenzene,the major product in the alkylation of dimethoxy benzene?Would you expect either of the following compounds to be formed as side products:1,3-di-t-butyl-2,5-dimethoxybenzene or 1,4-dimethoxy-2,3-di-t-butylbenzene? Why or why not?

matrix answered on 01/24/08:

The methoxy groups of 1,4-dimethoxybenzene are ortho,para directing. These direct the addition of the first tert-butyl group to an ortho position (the para positions are already occupied). The resulting compound now contains three ortho,para directing groups. The postion para to the first tert-butyl group is were the second tert-butyl group is directed.
.........
Electronic effects prevent the formation of 1,3-di-t-butyl-2,5-dimethoxybenzene.
........
1,4-Dimethoxy-2,3-di-t-butylbenzene is NOT formed because of steric effects. Two tert-butyl groups are too bulky to be on adjacent positions of the 1,4-dimethoxylbenzene.

cheriskae rated this answer Excellent or Above Average Answer

Question/Answer
cheriskae asked on 01/16/08 - Help please

What is the purpose of the phosphoric acid in "an alkene from alcohols" experiment? Why is phosphoric acid used rather than another strong acid such as hydrobromic acid?

matrix answered on 01/16/08:

Phosphoric acid is the catalyst in the reaction.
............
The dehydration of alcohols with acids is a general laboratory method for preparing alkenes. Strong mineral acids, such as sulfuric or phosphoric acids, usually are used as catalysts. Phosphoric acid rather than sulfuric acid is the preferred catalyst because
sulphuric acid produces messy results. Not only is it an acid, but it is also a strong oxidising agent. It oxidises some of the alcohol to carbon dioxide and at the same time is reduced itself to sulphur dioxide. Both of these gases have to be removed from the alkene usually by washing.

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Question/Answer
Jessica106 asked on 12/19/07 - Chemistry.. Calculating Mass

Someone please help me I am in Chemistry 20 and am having trouble understanding how to start solving this equation...


What mass of copper (II) hydroxide precipitate is produced by the reaction in solution of 2.67g of potassium hydroxide with excess aqueous copper (II) nitrate?

matrix answered on 12/19/07:

It helps to have a balanced equation for your question.
Cu(NO3)2 + 2 KOH ---> Cu(OH)2 + 2 KNO3
.......
Next determine the number of moles of your reactants.
2.67/56.1g/mole = 0.0476 moles of KOH
........
From your equation you can see that it takes two moles of to form one mole of Cu(OH)2.

2/1 = 0.0476/X
X = 0.0476/2 = 0.0238 moles of Cu(OH)2 will be formed.

0.0238 moles of Cu(OH)2 will have a mass of 2.32g
0.0238 moles x 97.6g/mole = 2.32g

Question/Answer
Ruth231 asked on 12/04/07 - Got some misunderstandings with this reaction:

6FeSO4+2NaNO3+4H2SO4=4H2O+2NO+Na2SO4+3Fe2(SO4)3 I suppose this reaction is right, but can't get the ionic reaction of this. I would appreciate any note about it.

matrix answered on 12/04/07:

6 FeSO4 + 2 NaNO3 + 4 H2SO4---->4 H2O + 2 NO + Na2SO4 + 3 Fe2(SO4)3
........
TOTAL IONIC EQUATION
6 Fe++ + 6 SO4-- + 2 Na+ + 2 NO3- + 8 H+ + 4 SO4-- ----> 4 H2O + 2 NO + 2 Na+ + SO4-- + 6 Fe+++ + 9 SO4--
.........
NET IONIC EQUATION
Subtract the ions that appear on both sides of the above equation.


6 Fe++ + 2 NO3- + 8 H+ ----> 4 H2O + 2 NO + 6 Fe+++

...........
The ionic equations are usually written with subscripts indicating if the species are in solution (aq), gas form (g) ,liquid (l) or solid( s).
6 Fe++(aq) + 2 NO3-(aq) + 8 H+(aq) ----> 4 H2O(l) + 2 NO(g) + 6 Fe+++(aq)

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Question/Answer
lulu7 asked on 11/27/07 - Chem Lab--Help with Ideal Gas Law

My chem lab is dealing with the ideal gas law (and Dumas method). I have the mass, volume, temperature; however, I don't know how to find the pressure or number of moles. The volatile compound is unknown and I'm looking for the molar mass of the compound? Please HELP!!!

matrix answered on 11/27/07:


The pressure you use is the atmospheric pressure in the lab. Either read the barometer in the lab or ask your instructor.
..........
You calculate the number of moles from all the data you have.
PV = nRT
Solve for n.
n = PV/RT
...........
Use the correct value for R depending on the units of your data.
http://en.wikipedia.org/wiki/Gas_constant
............

Once you have the number of moles you will be able to determine the molar mass using the mass of your sample.
molar mass = mass/number of moles

lulu7 rated this answer Poor or Incomplete Answer

Question/Answer
Jaylene45 asked on 11/27/07 - Balancing equations

How do I balance this equation
KCl)3 = __KCl + O2

matrix answered on 11/27/07:




2 KClO3 ---> 2 KCl + 3 O2

Question/Answer
Jaylene45 asked on 11/27/07 - Noble Gas

Do noble gases make compounds?

matrix answered on 11/27/07:



Xenon reacts with fluorine to form a number of compounds.Examples are xenon difluoride (XeF2), xenon tetrafluoride (XeF4), xenon hexafluoride (XeF6), oxyfluorides(XeOF2, XeOF4, XeO2F2, XeO3F2, XeO2F4) and oxides (xenon trioxide (XeO3), xenon tetroxide (XeO4)).
.........
Krypton reacts with fluorine to form krypton fluoride KrF2.
..........
Argon fluoride (ArF2) has been reported but its discovery has not been confirmed.
...........
Radon reacts with fluorine to form radon fluoride (RnF2).

Question/Answer
xrayrod asked on 11/13/07 - Mass, Volume, and Density at STP

What mass of propane gass, C3H8, must be combusted to produce 120.L of carbon dioxide at 115*C and 0.854 atmosphere?

matrix answered on 11/14/07:

PV = nRT
Solve for n
n = PV/RT
n = (0.854)(120)/0.082057)(388K) = 3.22 moles
........
3.22 x 44.1 g/mole = 142 g
........
Gas constant
http://en.wikipedia.org/wiki/Gas_constant

Gas Laws
http://www.pinkmonkey.com/studyguides/subjects/chem/chap6/c0606801.asp



Question/Answer
misty712 asked on 11/14/07 - synthesis of K3[Fe(C2O4)3]3H2O

Hi,
In lab, Fe(NH4)2(SO4)2-6H2O was used to synthesize K3[Fe(C2O4)3]3H2O or K[Fe(C2O4)2]-2H2O. I need to show the reaction and balance it to show the two percent yields for each possible product. It says to use the 3 main reactants in the equation and then show how they form the product. I was assuming that the three main products were the iron ammounium sulfate hydrated salt + K2C2O4 + H2C2O4 because in the worksheet, the H2O2 and H20 are shown over the arrow (I am assuming as catalysts?) Then the product would be one of the two products + NH4 +SO4 + ??? maybe water? I am not sure how to write the reaction or balance it since the water is connected. Thanks!!!

matrix answered on 11/14/07:

Hello misty
I am not sure of your question.
From your question "I was assuming that the three main products were the iron ammonium sulfate hydrated salt + K2C2O4 + H2C2O4 ".

These are reactants (or starting materials),they are NOT products.

...........
I will give you the balanced equation and if your need more then give more details.
........
The iron is being oxidized by the hydrogen peroxide from Fe^2+ to Fe^3+.
.........
2 (NH4)2Fe(SO4)2 + 3 H2C2O4 + 4 H2O + H2O2 + 3 K2C2O4 -----> 2 K3[Fe(C2O4)3]·3H2O + 2 (NH4)2SO4 + 2 H2SO4

Question/Answer
slksrkhrr asked on 11/01/07 - Percent Yeild

If 1.65g of Cu(No3)2 is obtained from allowing 0.85g of Cu to react with excess HNO3. What is the percent Yield of the reaction. I have balnaced the equation as follows and tried to solve it but I got a weird answer. Please Help
CU(s)+4HNO3(aq)-->Cu(NO3)2(aq)+2H2)(l)+2NO2(g)

matrix answered on 11/01/07:




The correct equation is below. I believe you meant 2 H2O instead of 2 H2.
4 HNO3(aq) + Cu(s) ==> Cu(NO3)2(aq) + 2 NO2(g) + 2 H2O(l)
.................
0.850/63.5 = 0.0134 moles of Cu
You started with 0.0134 moles of Cu and this should form 0.0134 moles of Cu(NO3)2
................
0.0134 x 187.6 = 2.44 g of Cu(NO3)2 is theoretical yield.
.........
1.65/2.44 x 100 = 67.6% yield

slksrkhrr rated this answer Excellent or Above Average Answer

Question/Answer
cheriskae asked on 10/30/07 - Help

I don't know how to solve this : Help please
After a number of test runs, Helen can reliably get 55% yield in her synthesis of aspirin.How much aspirin would she make if she had as much acetic anhydride as she wanted, but only 4g of salicylic acid? What was her theoretical yield?

Salicylic acid MW 138.1
Acetic anhydride MW 102 density 1.08
Acetylsalicylic acid MW 180.15

matrix answered on 10/30/07:

4.00/138.1 = 0.0290 moles of salicylic acid
.........
This will give a theoretical yield of 0.0290 moles of aspirin.
.........
Since the actual yield is 55% then 0.0290 x 0.55 = 0.016 moles or 2.88g of aspirin

cheriskae rated this answer Excellent or Above Average Answer

Question/Answer
ReginaD asked on 10/29/07 - Stoichemistry

The reaction of salicylic acid with acetic anhydride yields aspirin and acetic acid. Waht is the theoretical yield of aspirin if 85 grams of salicylic acid is treated with excess acetic anhydride?

matrix answered on 10/29/07:

Determine the number of moles of salicylic acid.
85g/138 g/mole = 0.62 moles
.......
0.62 moles is the theoretical yield of aspirin.
0.62 moles x 180 g/mole = 112g

ReginaD rated this answer Excellent or Above Average Answer

Question/Answer
aliceclin asked on 10/28/07 - Douglasite

Hey matrix, I've got a questiong for you.

Douglasite is a mineral with the formula 2 KCl·FeCl2·2 H2O. Calculate the mass percent of douglasite in a 597.5 mg sample if it took 37.20 mL of a 0.1000 M AgNO3 solution to precipitate all of the Cl - as AgCl. Assume the douglasite is the only source of chloride ion.

I don't know how to balance it, if I need to? and how to find the mass percent.

matrix answered on 10/28/07:

Douglasite is 45.48 Cl-
35.45/311.88 x 100 = 45.48%Cl-
..........
37.20ml x 0.1000M = 3.720 mmoles of AgNO3 used and this is the number of mmoles of AgCl formed.
...........
3.720 x 35.45mg/mmole = 131.9mg of Cl- in your sample.
You know that 45.48 of Douglasite is Cl-.
45.48%X = 131.9
X = 131.9/0.4548 = 290.1 mg is weight of Douglasite in sample.
..........
290.1/597.4 x 100 = 48.55% Douglaste in sample.

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Question/Answer
aliceclin asked on 10/28/07 - metal identification

A 1.00 g sample of an alkaline earth metal chloride is treated with excess silver nitrate. All of the chloride is recovered as 1.38 g of silver chloride. Identify the metal.

I balanced the equation,
Cl + AgNO3 --> AgCl + NO3

what do I do now? how do I identify?
thanks

matrix answered on 10/28/07:

Remember to put charges on ions when you balance equations
Cl- + Ag+ ----> AgCl
............

You need the percent of Cl- in AgCl
35.45/ 143.3 x 100 = 24.74%
In your sample of 1.38g you have 0.341g of Cl-

.......
Since you started with 1.00g of unknown chloride and you know it contains 0.341g of Cl-
the starting material is an alkaline earth chloride that contains 34.1% Cl- and 65.9% X.
You need to decide which of the alkaline earth metal chlorides(BeCl2,CaCl2,MgCl2,SrCl2,BaCl2,RaCl2) has these percentages.

The alkaline earth metal chloride closest to these percentages is BaCl2.

..........
The website below is useful for calculating percentages.
http://www.ch.cam.ac.uk/magnus/MolWeight.html

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Question/Answer
aliceclin asked on 10/28/07 - Oxidation and Reduction

If 2.02 g of copper(II) chloride dihydrate is reduced by Mg(s), what is the minimum mass of Mg(s) required for this reduction?

all I could think to do is:
CuCl2 + Mg(2+) __> MgCl2 + Cu(2+)

thanks

matrix answered on 10/28/07:

Why did you use Mg(2+) in your equation????
Mg metal is zero.
The correct solution is below.




CuCl2 + Mg ---> Cu + MgCl2

The molar weight of CuCl2•2H2O is 170.48

Calculate the number of moles of CuCl2•2H2O
2.02/170.48 = 0.0118 moles

It requires one mole of Mg for each mole of CuCl2•2H2O.
You need 0.0118 moles of Mg
0.0118 x 24.31 = 0.287 g of Mg

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Question/Answer
chem142 asked on 10/28/07 - Stoichiometry

If 2.02 g of copper(II) chloride dihydrate is reduced by Mg(s), what is the minimum mass of Mg(s) required for this reduction?

matrix answered on 10/28/07:

CuCl2 + Mg ---> Cu + MgCl2

The molar weight of CuCl2•2H2O is 170.48

Calculate the number of moles of CuCl2•2H2O
2.02/170.48 = 0.0118 moles

It requires one mole of Mg for each mole of CuCl2•2H2O.
You need 0.0118 moles of Mg
0.0118 x 24.31 = 0.287 g of Mg

chem142 rated this answer Excellent or Above Average Answer

Question/Answer
bkmorgan asked on 10/27/07 - Standard Temperature and Pressure

How many moles of propane (C3H8) would a 2.50 L tank contain at STP?

matrix answered on 10/27/07:

One mole of any gas has a volume of 22.4 L at STP.

2.50/22.4 = 0.112 moles

Question/Answer
marietoma asked on 10/23/07 - help with chem please

How many grams of Kl are in 25.0 mL of a 3.0 % (m/v) Kl solution?

matrix answered on 10/23/07:

A solution that is 3.0% (m/v) contains 3.0 g of solute in 100 ml of solution.

3.0 x (25/100) = 0.75 g of KI

Question/Answer
cheriskae asked on 10/21/07 - help

If you have ligroine and cyclohexane ,how do you know which is saturated or unsaturated?

matrix answered on 10/22/07:

Hello
This is a strange question because ligroin(e) is a material of variable composition.It contains many different saturated hydrocarbons. It may contain some cyclohexane.


Ligroine and cyclohexane are both saturated.


Below is a textbook definition of ligroine:
"Ligroin is a refined saturated hydrocarbon petroleum fraction similar to petroleum ether used mainly as a laboratory solvent. It predominantly consists of C7 through C11 in the form of about 55% paraffins, 30% monocycloparaffins, 2% dicycloparaffins and 12% alkylbenzenes. It is nonpolar. Generally laboratory grade ligroin boils at 60 to 90 °C, but the following fractions of petroleum ether are commonly available: 30 to 40 °C, 40 to 60 °C, 60 to 80 °C, 80 to 100 °C and sometimes 100 to 120 °C. The 60 to 80 °C fraction is often used as a replacement for hexane."

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Question/Answer
cheriskae asked on 10/20/07 - help please

Cyclohexene reacts with a high concentration of bromine to give what coumpound? What is its stereochemistry?
I don't know how to draw a stucture of the compound formed when cyclohexene dissolves in a concentrated sulfuric acid.


matrix answered on 10/20/07:

Cyclohexene reacts with bromine to give trans-1,2-dibromocyclohexane.
See website below for a drawing of the structure.
http://www.uni-regensburg.de/Fakultaeten/nat_Fak_IV/Organische_Chemie/Didaktik/Keusch/D-Addit_ar-e.htm

Cyclohexene reacts with sulfuric acid to form cyclohexyl hydrogensulfate.This is soluble in sulfuric acid.

C6H5-HSO4

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Question/Answer
cheriskae asked on 10/20/07 - Question

If I combine Pinene with permanganate, is it saturated or unsaturated? how do I know?
Same question by combining paraffin + permanganate, paraffin +sulfuric acid

matrix answered on 10/20/07:

The pinene makes the purple permanganate turn yellow-brown. This is a positive test for unsaturation.
(The -ene ending of pinene gives you a hint that it is unsaturated)

Paraffin is a saturated material and will give negative permanganate and sulfuric acid tests.

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Question/Answer
cheriskae asked on 10/12/07 - Help

After doing distillation, if you consider dividing up the distillate collected into thirds: the first third, the middle, and the last third.What can you conclude about the purity of the first and last from the simple distillation, and from the fractional distillation, in other words will they have the same purity?

matrix answered on 10/14/07:

Hello cheriskae

This is a difficult question to answer because of the variables involved. I will give a simple answer.Let me know if you need a more detailed answer.


In a simple distillation where only one fraction is collected then if you divide the distillate into three parts, each of these parts will have the same purity.

In a fractional distillation where you collect fractions based on increasing boiling point then if you collect three fractions, the first will consist of mainly the material with the lower boiling point. The second fraction will be a mixture of the two materials and the third will be mainly the material having the higher boiling point.

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Question/Answer
RWICKENHEISER asked on 10/07/07 - SHOW HOW TO GET THIS BALANCED EQUATION

I HAVE THE ORIGINAL QUESTION AND THE ANSWER. HOW DO I GET THE BALANCED EQUATION. I NEED TO KNOW THE STEPS.

Al+ MnO4=MnO2+Al(OH)4

BALANCED EQUATION

Al+MnO4+2H2O=MnO2+Al(OH)4

matrix answered on 10/07/07:

First neither of your equations are correct.
You must indicate the charges.
It is MnO4- and Al(OH04- There should be a minus charge on each of these two materials.

The correctly balanced equation is
Al + MnO4- + 2 H2O ----> MnO2 + Al(OH)4-

The steps used to balance reactions such as this are shown on the following website.

http://www.helium.com/tm/596616/faced-redox-reaction-sadly

Please read this to understand the steps.
Ask me if you do not understand.

Question/Answer
lulu7 asked on 09/30/07 - Limiting Reactants

1.85 mol NaOH and 1.00 mol CO2 react as follows:
2 NaOH(s) + CO2(g) = Na2CO3(s) + H2O (l)
a. What is the limiting reactant?

b. How many moles of Na2CO3 can be produced?

c. How many moles of excess reactant remain after the completion of the reaction?

Please answer what you can and show your work -- I'm completely lost on this!

matrix answered on 10/01/07:



2 NaOH(s) + CO2(g) ----> Na2CO3(s) + H2O (l)

(a) From your equation you need 2 moles of NaOH for each mole of CO2. Since you only have 1.85 moles of NaOH it is the limiting reagent.

(b) The CO2 is the excess reagent.
2/1 = 1.85/X
X = (1.85 x 1)/2 = 0.925 moles of CO2 is used in the reaction. This will make 0.925 moles of Na2CO3.

(c) CO2: 1.00 - 0.925 = 0.075 moles of CO2 remain unreacted.

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Question/Answer
cheriskae asked on 09/30/07 - Help please

What will be the appearance of a TLC plate if a solvent of too low polarity is used for the development? too high polarity?

Why does the lid of the jar need to be on while developing your TLC plate?

What problem will ensue if the level of the developing liquid is higher than the applied spot in a TLC analysis?

matrix answered on 09/30/07:

(1)What will be the appearance of a TLC plate if a solvent of too low polarity is used for the development? too high polarity?

TOO LOW POLARITY. The spots will stay on or too near the origin.
TOO HIGH POLARITY. The spots will be at the top of the plate (solvent front).
In thin layer chromatography you want the spots to have a Rf of between 0.2 and 0.8.

(2)Why does the lid of the jar need to be on while developing your TLC plate?

The reason for covering the jar is to make sure that the atmosphere in the beaker is saturated with solvent vapor.
To help this, the jar is often lined with some filter paper soaked in solvent.Saturating the atmosphere in the jar
with vapor stops the solvent from evaporating as it rises up the plate. The solvent needs to go up the plate to NEAR the top.

(3)What problem will ensue if the level of the developing liquid is higher than the applied spot in a TLC analysis?

The spot will NOT move up the plate but will spread out as blob and contaiminate the solvent in the jar.

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Question/Answer
lulu7 asked on 09/30/07 - Chemical Reaction

Is Fe2O3+3 CO=2 Fe+3 CO2 a precipitation reaction, an acid-base reaction, or an oxidation-reduction reaction and how do you know?

matrix answered on 09/30/07:

In oxidation-reduction reactions something is oxidized and something is reduced. This is not true for the other kinds of reactions.



Fe2O3 + CO ----> Fe + CO2
In this reaction the iron is being reduced (going from +3 to zero) and the carbon is being oxidized (going from +2 to +4).

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Question/Answer
Wendy0920 asked on 09/23/07 - Chemistry equation

Use the following balanced equation:
2 C6H14 + 19 O2 -- 12 CO2 + 14 H2O

How many grams of C6H14 are required to produce 1.5 moles of carbon dioxide?

matrix answered on 09/25/07:

2 C6H14 + 19 O2 --> 12 CO2 + 14 H2O
2 moles of hexane gives 12 moles of carbon dioxide then X moles will give 1.5 moles.
2/12 = X/1.5
X = 3/12 = 0.25 moles
0.25 moles of hexane is 21.6
0.25 x 86.2 = 21.6 g
This should be rounded to 22 grams because you have only two significant figures.

Question/Answer
twoego asked on 09/25/07 - Chemistry

What is the mass in grams if 30.0 ml of a liquid if its density is 0.60g/ml?

matrix answered on 09/25/07:

Density = mass/volume
Solve for mass
Mass = density X volume

30.0 ml X 0.60g/ml = 18 grams

Question/Answer
cheriskae asked on 09/23/07 - Help please- Organic chemistry

Why do we have to ice a tea solution before moving on to the extraction with dichloromethane?
And what is the purpose of adding calcium chloride to dichloromethane after extracting?

matrix answered on 09/23/07:

Dichloromethane has a boiling point of 40ºC.You need to cool the tea solution before mixing with the dichloromethane so it will boil out or release a large amount of dichloromethane vapor into your face and the lab.

The calcium chloride is used as a drying agent. It removes the small amount of water dissolved in the dichloromethane.

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Question/Answer
KatiBabi asked on 09/23/07 - Moles of O2 that are needed to burn 1.5 mol of C8H18

2 C8H18(l) + 25 O2(g) 16 CO2(g) + 18 H2O(l)

(a) How many moles of O2 are needed to burn 1.50 mol of C8H18?

matrix answered on 09/23/07:

Hello KalBabi
Once you have a correctly balanced equation questions such as this become simple math questions.
It takes 25 moles of O2 for 2 moles of octane then it will take X moles for 1.50 moles of octane.

25/2 = X/1.5
Solve for X
X = (25x1.5)/2 = 18.75
This should be rounded to 18.8 moles of O2 because of the number of significant figures you have with 1.50 (3 significant figures).

2 C8H18(l) + 25 O2(g)---> 16 CO2(g) + 18 H2O(l)

Question/Answer
zardaz asked on 09/20/07 - Chem Help
Chem help

how many C atoms are in 5.00 grams of benzene C6H6?

matrix answered on 09/20/07:

5.00g /78.1g/mole = 0.0640 moles of benzene.
Since benzene has 6 carbon atoms per mole then you have 6 x 0.0640 = 0.384 moles of carbon atoms in your sample.

1 mole of carbon contains 6.022 x 10^23 atoms.

In 5.00 g of benzene there are
0.384 x 6.022 x 10^23 = 2.31 x 10^23 carbon atoms

Question/Answer
bmise24 asked on 09/20/07 - Calculation Help, Not sure where to start?

Barium oxide reacts with hydrochloric acid producing barium chloride and water. Calculate how much water (g) is produced from 35g of barium oxide and 25g of hydrochloric acid.

Balanced equation = BaO + 2HCl - BaCl2 + H2O

matrix answered on 09/20/07:

BaO + 2HCl----> BaCl2 + H2O
From your equation one mole of BaO gives one mole of H2O.

BaO: 35g / 153g/mole = 0.23 moles
This will make 0.23 moles of H2O

0.23moles X 18g/mole = 4.1 g of H2O


HCl: 25g / 36.5 = 0.68 moles
From equation you need two moles of HCl to react with each mole of BaO.
For 0.23 moles of BaO you would need 0.46 moles of HCl. Since you have 0.68 moles of HCl you have more HCl than you need. The limiting reagent is the BaO.




Question/Answer
Zenz04 asked on 09/13/07 - Balanced equation help?

Can you help me with the balanced equation for dissolving an Alka Seltzer tablet in water? I think it's:

C15NaH19O11CO3?(aspirin,citric acid,sodium bicarbonate, is an Alka Seltzer tablet I think)+H2O = C02+Na3C6H5O7

matrix answered on 09/13/07:

The aspirin (acetylsalicylic acid) is not an active ingredient in the effervescent action of Alka-Seltzer, but the baking soda (sodium bicarbonate) and citric acid are active.

C6H8O7 + 3 NaHCO3--→ 3 H2O + 3 CO2 + Na3C6H5O7

Question/Answer
Chance asked on 09/10/07 - Chemistry

what is the formula for compound containing lithium and floride, caloium and flurino, maggnesium and oxygen?

matrix answered on 09/10/07:

LiF

CaF2

MgO

Question/Answer
Zenz04 asked on 09/08/07 - I'm stuck and need help bad.

A certain mass of sodium hydroxide is required to produce 3 moles of water in the reaction 2NaOH + CO2 = Na2CO3 + H2O. Which of the following relationships determines the mass of NaOH required?

a. 3 mol H2O x (40g NaOH/2 mol NaOH) x (1 mol H20/18gH2O)

b. 3 mol H2O x (1 mol H20/2 mol NaOH) x (1 mol NaOH/40g NaOH)

c. 3 mol H2O x (2 mol NaOH/1 mol H2O) x (40g NaOH/1 mol NaOH)

d. 2 mol NaOH x (3 mol H2O/2 mol NaOH) x (18g H2)/1 mol H20)

I think it's D. But I'm not to sure.

matrix answered on 09/09/07:

Answer (c) is correct.

From equation:
For 1 mole of H2O you need 2 moles of NaOH.

If you want 3 moles of H2O then you need 3 x 2 moles of NaOH ---> 6 moles of NaOH.

1 mole of NaOH is 40g
6 moles x 40g/mole = 240 g NaOH

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Question/Answer
cheriskae asked on 09/09/07 - Help Please


Sally is looking for a recrystallization solvent for an organic compound she just synthesized. What solubility properties should she be looking for an ideal recrystallization solvent?

matrix answered on 09/09/07:

A good recrystallization solvent should:

(1) dissolve a moderate quantity of the substance to be purified at an elevated temperature, but only a small quantity at lower temperatures
(2) not react with the material to be purified
(3) either dissolve impurities readily at a low temperature or not dissolve them at all
(d) be easily removable from the purified product.This last requirement usually means that the solvent must have a relatively low boiling point and evaporate readily.

Read for more details.
http://designer-drug.com/pte/12.162.180.114/dcd/chemistry/equipment/recrystallization.html

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Question/Answer
frejalaub asked on 09/02/07 - net ionic help


aqueous solutions of K2C2O4 and CuSO4 are mixed to form a precipitate. I thought maybe CuCO3 + CO2 were the products but I can't get it balance. Please help.

matrix answered on 09/02/07:

The solid is cupric potassium oxalate.

2 K2C2O4 + CuSO4 ----> K2Cu(C2O4)2 + K2SO4

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Question/Answer
horban asked on 08/30/07 - I need HELP! please show me formula and how to solve this.

a 1.543g sample containing sulfate ion was treated with barium cholride reagent, and 0.2243 grams of barium sulfate was isolated. Calculate the percentage of sulfate ion in the sample.

please show me how to solve this

matrix answered on 08/30/07:

M.Wt of BaSO4 is 233.395
At.Wt. of Ba is 137.904
137.904/233.395 x 100 = 58.84%
Ba is 58.84%
SO4 is 41.16%

0.2243g x 41.16% = 0.09232g is amount of SO4-- in sample.
0.09232/1.543 x 100 = 5.98% This is % of SO4-- in sample.

Question/Answer
horban asked on 08/30/07 - oxidation state

What is the oxidation state of aluminum in KAl(SO4)2 (12H2O)?

matrix answered on 08/30/07:

KAl(SO4)2*(12H2O)
The oxidation number of Aluminum (Al) is +3.

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Question/Answer
[quinn] asked on 08/15/07 - balanced chemical equation

could you please help me with the balanced chemical equation for the complete combustion of 2,2-dimethylhexane?

matrix answered on 08/15/07:

Hello Quinn

All the carbon is converted to CO2 and all the hydrogen is converted to H2O.

2 C8H18 + 25 O2 ---> 16 CO2 + 18 H2O

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Question/Answer
lapaix4mum asked on 07/05/07 - acids bases and salts

why is (Na2O)Na crayying 2 rather than O

matrix answered on 07/05/07:

Sodium in its compounds has a valence of +1
Oxygen has a valence of -2.

It takes two sodium ions [2 x (+1)] to balance the -2 charge of of the oxygen.
This is why the formula is Na2O.

Question/Answer
balla4791 asked on 06/03/07 - how many grams of KNO3 should be used to prepare a 2.00L of a .500M solution


Questions

how many grams of KNO3 should be used to prepare a 2.00L of a .500M solution?


matrix answered on 06/05/07:

The molecular weight of KNO3 is 101.10

One liter of 0.500M will contain 101.10/2 = 50.6 grams of KNO3.
Two liters will contain 101 grams.

Question/Answer
ritu90 asked on 06/04/07 - isomers

hiii matrix....
would u help me out with 2 questions...??..thanks
Draw and name all the isomers of C8H18 which hav single side chain.
Draw and name all the isomers of C8H18 which have two side chains.

thank you
ritu

matrix answered on 06/05/07:

I cannot draw structures with my keyboard but I will list the compounds. The names tell you the structures.For example, for 2-methylheptane first draw 7 carbons in a line (heptane) then put a carbon on the second carbon in the line. Finally fill in with hydrogens.

Single Side Chain
2-methylheptane
3-methylheptane
4-methylheptane
3-ethylhexane



Double Side Chain
2,2-dimethylhexane
2,3-dimethylhexane
2,4-dimethylhexane
2,5-dimethylhexane
3,3-dimethylhexane
3,4-dimethylhexane
3-ethyl-2-methylpentane
3-ethyl-3-methylpentane

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Question/Answer
dredling asked on 05/24/07 - Double displacement question?

I have a double displacement of NaOH and NiCl2 and I need to write a balaced equation, but I'm unsure how to get it started as far as what elements will be displaced.

matrix answered on 05/24/07:

2 NaOH + NiCl2 ---> 2 NaCl + Ni(OH)2

http://chemistry.about.com/cs/generalchemistry/a/aa072103a.htm

http://dl.clackamas.edu/ch104-04/double.htm

Question/Answer
lizarl asked on 05/23/07 - Zinc chloride

Zn + 2HCl → ZnCl2 + H2

If 0.600 gram of zinc is used, what is the amount of zinc chloride that is produced in the reaction?

matrix answered on 05/23/07:

0.600/65.4 = 0.00917 moles of zinc

This will make 0.00917 moles of ZnCl2

0.00917 x 136.3 = 1.25 grams of ZnCl2

Question/Answer
lfcsg asked on 05/22/07 - chem help again


A zinc powder is added to a solution of copper(II) sulfate. Which of the following best represents the balanced, net ionic equation?

a. Cu2+(aq) + Zn(s) Zn2+(aq) + Cu(s)
b. CuSO4(aq) + Zn(s) ZnSO4(aq) + Cu(s)
c. H+(aq) + OH-(aq) H2O(aq)
d. Cu2+(aq) + Zn2+(aq) Zn2+(aq) + Cu2+(aq)
e. CuSO4(aq) + Zn(aq) ZnSO4(aq) + Cu(aq)

matrix answered on 05/22/07:

A zinc powder is added to a solution of copper(II) sulfate. Which of the following best represents the balanced, net ionic equation?

a. Cu2+(aq) + Zn(s)----> Zn2+(aq) + Cu(s)

Question/Answer
BxDiamond asked on 05/10/07 - Balancing oxidation reduction reactions by the ion electron method

Identify the oxidation and reduction half reactions, the elements oxidized and reduced and oxidizing and reducing agents fot the reaction.

In Acid

Cu+NO3-> Cu+2 +NO2

matrix answered on 05/11/07:

Cu(s) + HNO3(aq) --> Cu(NO3)2(aq) + NO2(g)

Step 1: Net ionic equation
Cu(s) + H+(aq) + NO3-(aq) ---> Cu2+(aq) + NO3-(aq) + NO2(g)

Step 2 & 3: Half-reactions
Cu(s) ---> Cu2+(aq) (oxidation,Cu is oxidized)

NO3-(aq) ---> NO3-(aq) + NO2(g) (reduction,nitrogen is reduced)

Copper is the reducing agent. It is oxidized in the reaction.
Nitrogen is the oxidizing agent. It is reduced in the reaction.

Step 4: Mass Balancing
Cu(s) ---> Cu2+(aq) (oxidation)

2NO3-(aq) + 2H+(aq) ---> NO3-(aq) + NO2(g) + H2O(l) (reduction)

Step 5: Charge Balancing
Cu(s) ---> Cu2+(aq) + 2e- (zero charge on both sides)

2NO3-(aq) + 2H+(aq) + e- ---> NO3-(aq) + NO2(g) + H2O(l) (-1 charge on both sides)

Step 6: Multiply to equalize electrons (multiply the reduction equation by 2)
Cu(s) ---> Cu2+(aq) + 2e-

4NO3-(aq) + 4H+(aq) + 2e- ---> 2NO3-(aq) + 2NO2(g) + 2H2O(l)

Step 7: Add the reactions (electrons cancel)
4NO3-(aq) + 4H+(aq) + Cu(s) ---> Cu2+(aq) + 2NO3-(aq) + 2NO2(g) + 2H2O(l)

Step 8: Check atoms and charge are balanced

Step 9: Rewrite equation in molecular form
4HNO3(aq) + Cu(s) ---> Cu(NO3)2(aq) + 2NO2(g) + 2H2O(l)

Some websites that may help.
http://www.chemtutor.com/redox.htm

http://preparatorychemistry.com/Bishop_Balancing_Redox.htm

http://www2.wwnorton.com/college/chemistry/gilbert/concepts/chapter5/ch5_6.htm


Question/Answer
lfcsg asked on 05/05/07 - chem

anyone know the concentration of NH4+ in a 2.528 M (NH4)2SO4 solution

matrix answered on 05/05/07:

2 x 2.528 = 5.056 M in NH4+.

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Question/Answer
cod143 asked on 04/25/07 - Net Ionic Equations

Write molecular, ionic, and net ionic equations for the neutralization of magnesium carbonate, MgCO3 (Tums and Di-Gel), with HCl.

thanks!

matrix answered on 04/25/07:

MOLECULAR
MgCO3 + 2 HCl ----> MgCl2 + CO2 + H2O

IONIC
MgCO3(s) + 2 H+(aq) + 2 Cl-(aq) -----> Mg++(aq) + 2 Cl-(aq) + H2O + CO2(g)

NET IONIC
MgCO3(s) + 2 H+(aq) ---> Mg++(aq) + H2O + CO2(g)

Question/Answer
mcmufftcp asked on 04/11/07 - Preparation of Aspirin

Hi-
I'm going to be doing a prep of aspirin lab. To test the purity of the aspirin, we first have to test phenol, 2-propanol, benzoic acid and salicylic acid with [Fe(III)(NO3)3] to see which will bind with Fe3+ by turning the soln purple. I know that Fe3+ will bind with the -OH of phenol and not benzoic acid because it is a carboxylic acid. Will Fe3+ bind with the -OH in 2-propanol and salicylic acid??
Next, we test the purity of our aspirin vs a commercial grade by seeing if the ASA will bind with Fe3+. I think the commercial grade will for sure NOT bind with the Fe3+. If the experimentally prep ASA does, does that mean it has salicylic acid impurities in it???
Thank you for any insight you may be able to provide.

matrix answered on 04/11/07:

Phenol and salicylic acid will give a positive test. Salicylic acid is a phenol.

Benzoic acid and 2-propanol will NOT give a positive test.

The Fe+++ ion test is for phenols NOT for alcohols or carboxlic acids.

Pure aspirin will NOT give positive test.

Impure aspirin will give positive test if it contains some unreacted salicylic acid.

Old commercial aspirin that has been stored in moist air for long periods will probably give a positive test because some of the acetylsalicylic acid is hydrolyzed to salicylic acid and acetic acid.

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Question/Answer
jc6391 asked on 04/11/07 - please help

calculate the volume in liters.
2.00 mol of H2 at 300 K and 1.25 atm.

matrix answered on 04/11/07:

PV = nRT

Solve for V using following values.
V = nRT/P = 39.4 liters


n = 2.00 moles
R = 0.082057 [L · atm / K · mol]
T = 300K
P = 1.25 atm

R is universal gas constant.
See chart in following website.Use value that has same units as your problem.

http://en.wikipedia.org/wiki/Gas_constant

Question/Answer
erikaj2 asked on 04/10/07 - double replacement rxn

How do you predict this double replacement reaction: barium chloride trihydrate + silver nitrate?

matrix answered on 04/10/07:

BaCl2 + 2 AgNO3 ----> 2 AgCl + Ba(NO3)2

Question/Answer
10MillionJujubes asked on 04/08/07 - I need help on chemistry!

How many liters of CO2 gas are evolved when 2.00g of NaHCO3 react completely according to the equation NaHCO3(aq) + H+(aq) = H2O(l) + CO2(g) + Na+(aq)?
(given the density of CO2 gas is 1.961 g/l)

matrix answered on 04/08/07:

NaHCO3(aq) + H+(aq) ----> H2O(l) + CO2(g) + Na+(aq)?

2.00/84.0 = 0.024 moles of NaHCO3
This will produce 0.024 moles of CO2

1 mole of any gas is 22.4 liters at STP.
22.4 x 0.024 = 0.754 liters

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Question/Answer
10MillionJujubes asked on 04/08/07 - Mass relations in Reactions

What mass in grams of sodium hydroxide is produced if 20.0 g of sodium metal are reacted with excess water according to the chemical equation 2Na(s) + 2H2O(l)?
2NaOH(aq) + H2(g)?

matrix answered on 04/08/07:

2 Na(s) + 2 H2O(l)----> 2 NaOH(aq) + H2(g)?

20.0/23.0 = 0.87 moles of sodium
This will produce 0.87 moles of NaOH

0.87 x 40.0 = 34.8 grams

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Question/Answer
10MillionJujubes asked on 04/08/07 - HELP!Chemistry!

Your friend sits on a 25.0L ball, decreasing the volume to 17.5 L. What is the pressure inside the ball if the air pressure that day is 100 kPa?

matrix answered on 04/08/07:

P x V (initial) = P x V (final)

P (final) = P (initial) x [V(initial)/V(final)]
P = 100 x (25.0/17.5) = 143 kPa

10MillionJujubes rated this answer Excellent or Above Average Answer

Question/Answer
yakax007 asked on 04/05/07 - Net Ionic Help Needed!!!!

I have no clue what I am doing wrong here. I am 95% sure these are right but it keeps telling me they are wrong. PLEASE help!!!!

K2S + ZnSO4
... Zn^2+ + S^2- -> ZnS

CsOH + FeCl3
... Fe^3+ + 3OH^1- -> Fe(OH)3

FeSO4 + K3PO4
... 3Fe^2+ + 2PO4^-3 -> Fe3(PO4)2

matrix answered on 04/05/07:

K2S + ZnSO4
Zn^2+(aq) + S^2-(aq) -> ZnS(s)

CsOH + FeCl3
Fe^3+(aq) + 3 OH^1-(aq) -> Fe(OH)3(s)

FeSO4 + K3PO4
3 Fe^2+(aq) + 2 PO4^-3(aq) -> Fe3(PO4)2(s)

Rules for writing Net Ionic Equations
http://www.chem.vt.edu/RVGS/ACT/notes/Notes_on_Net_ionic_rxns.html

Question/Answer
weirdo asked on 04/03/07 - help!

calculate the number of grams of hydrogen in 4.50 mol H2SO4

matrix answered on 04/03/07:

4.50 moles of H2SO4 contains 4.50 moles of H2.

The molecular weight of H2 is 2.016.

4.50 x 2.016 = 9.07 grams

Question/Answer
sksara asked on 04/03/07 - I need help with Molarity ASAP Please!!!

Given the reaction:
Pb(NO3)2 + 2KCl = PbCl2 + 2KNO3

What is the molarity of 20.0 mL of KCl solution that reacts with 30.0 mL of 0.400 M Pb(NO3)2?

matrix answered on 04/03/07:

Pb(NO3)2 + 2 KCl ---> PbCl2 + 2 KNO3
From your equation you see that one Pb(NO3)2 will react with 2 KCl.
The normality of the Pb(NO3)2 solution is twice the molarity. It is 0.800 N

milliters x normality give milliequivalents

In titrations: At the equivalent point the number of milliequivalents on the left is equal to the number of milliequivalents on the right.

20.0 ml x X molarity = 30.0 ml x 0.800 N
20.0 X = 24.0
X = 1.20 M molarity of KCl

Question/Answer
VioletPepper asked on 03/24/07 - In Isotonic, Hypertonic nad Hypotonic solution.... does glucose matter?

A 0.9% NaCl (saline) and 5% glucose solutions are considered isotonic to red blood cells.

But what will happen to red blood cells placed in a 0.9% glucose solution?

matrix answered on 03/24/07:

A 0.9% NaCl (normal saline solution) and 5% glucose solutions are isotonic with body fluids.

Red blood cells placed in an isotonic solution will retain their normal size, that is they neither gain nor lose water by osmosis.

Question/Answer
stevieg asked on 03/22/07 - moles

Determine the moles for ammonium iodide in 5.810 grams

matrix answered on 03/22/07:

5.810 / 144.943 = 0.040087 ---> 0.0401 moles

stevieg rated this answer Bad/Wrong Answer

Question/Answer
stevieg asked on 03/22/07 - chem

A hygroscopic substance which absorbs water from the moist air and forms either a moist solid or solution. Which of the following compounds is hygroscopic?

a. silver(I) chloride, AgCl
b. sodium hydroxide, NaOH
c. calcium hydroxide, Ca(OH)2
d. znic chloride, ZnCl2

matrix answered on 03/22/07:

a. silver(I) chloride, AgCl ---- Not hygroscopic
b. sodium hydroxide, NaOH ---- Yes,it is hygroscopic
c. calcium hydroxide, Ca(OH)2 ---- Not hygroscopic
d. znic chloride, ZnCl2 ---- Yes,it is hygroscopic

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Question/Answer
stevieg asked on 03/22/07 - chem

How many grams of copper(II) nitrate could be formed from the reaction of 1.823 g of copper with excess HNO3?

matrix answered on 03/22/07:

1.823 / 63.5456 = 0.02869 moles
0.02869 x 187.56 = 5.381 grams

stevieg rated this answer Bad/Wrong Answer

Question/Answer
stevieg asked on 03/22/07 - moles

Determine the number of moles of silver nitrate in 6.90 grams? round it off

matrix answered on 03/22/07:

6.90 / 169.87 = 0.0406 ---> 0.041 moles

stevieg rated this answer Excellent or Above Average Answer

Question/Answer
anyajerae asked on 03/20/07 - moles

How many moles of sulfur are present in 6.0 moles of Al2(SO4)3

matrix answered on 03/20/07:

One mole of Al2(SO4)3 contains 3 moles of S.
6 moles of Al2(SO4)3 will contain 18 moles of S.

Question/Answer
TrynaPass asked on 03/18/07 - Mole ques

Consider the reaction

CH4 + 2O2 ----> CO2 + 2H2O

Exactly 14.5 moles of CO2 are produced upon reaction of 34.6 moles of O2 and how many moles of CH4??

matrix answered on 03/18/07:

34.6 moles of O2 is enough to react with 17.3 moles of CH4 which would produce 17.3 moles of CO2. Since you formed 14.5 moles of CO2 this tells you that the O2 is present in excess.This also tells you that all of the CH4 present reacted and since you get one mole of CO2 for every every mole of CH4, you must have started with 17.3 moles of CH4.

Question/Answer
TrynaPass asked on 03/18/07 - Mole quest

For the reaction

2 S(s) + 3 O2(g) ----> 2 SO3(g)

how much SO3 will be produced from 2.0 mol O2 and excess S?



1. 2.0 mol SO3
2. Cannot be determined unless the limiting reactant is known.
3. 0.75 mol SO3
4. 1.3 mol SO3

matrix answered on 03/18/07:

With excess sulfur
3 O2----> 2 SO3

3/2 moles = 2/X moles
X = (2x2)/3 = 1.3 moles SO3

TrynaPass rated this answer Excellent or Above Average Answer

Question/Answer
TrynaPass asked on 03/18/07 - another mole quest

When the reaction P4O10 + KOH -----> K3PO4 + H2O
is balanced, how much KOH is required to react with 3 moles of P4O10??

matrix answered on 03/18/07:

P4O10 + 12 KOH ---> 4 K3PO4 + 6 H2O

1/3 moles = 12/X moles
X = 36 moles

TrynaPass rated this answer Excellent or Above Average Answer

Question/Answer
dalexi asked on 03/18/07 - mole question

Consider the reaction

CH4 + 2O2 ---> CO2 + 2H2O

Exactly 14.5 moles of CO2 are produced upon reaction of 34.6 moles of O2 and how many moles of CH4?

matrix answered on 03/18/07:

34.6 moles of O2 is enough to react with 17.3 moles of CH4 which would produce 17.3 moles of CO2. Since you formed 14.5 moles of CO2 this tells you that the O2 is present in excess.This also tells you that all of the CH4 present reacted and since you get one mole of CO2 for every every mole of CH4, you must have started with 17.3 moles of CH4.

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Question/Answer
dalexi asked on 03/17/07 - mole question

burning 32g of ch4 in excess oxygen will produce how much co2 according to the equation:

CH4+2O2 ---> CO2+2H2O

a)4 mol
b)1 mol
c)2 mol
d)3 mol
e)32 mol

matrix answered on 03/17/07:

You have 2 moles of methane. This will give 2 moles of carbon dioxide.

dalexi rated this answer Excellent or Above Average Answer

Question/Answer
stevieg asked on 03/16/07 - Chemistry

number of moles of cobalt acetate in 4.88 grams?

matrix answered on 03/17/07:

Molecular weight of Co(OAc)2 is 177.02

4.88/177.02 = 0.0276 moles

stevieg rated this answer Excellent or Above Average Answer

Question/Answer
jannie asked on 03/16/07 - replacement

Which equation represents a double replacement reaction?

2 Na + 2 H2O 2 NaOH + H2
CaCO3 CaO + CO2
LiOH + HCl LiCl + H2O
CH4 + 2 O2 CO2 + 2 H2O

matrix answered on 03/16/07:

(1) 2 Na + 2 H2O---> 2 NaOH + H2
(2) CaCO3 ----> CaO + CO2
(3) LiOH + HCl ----> LiCl + H2O
(4) CH4 + 2 O2 ---> CO2 + 2 H2O

Rxn 1 is a single displacement or substitution reaction.

Rxn 2 is a decomposition reaction.

Rxn 3 is a double replacement reaction.

Rxn 4 is a combustion reaction.

Question/Answer
lisarob8 asked on 03/05/07 - net ionic equations

I'm having trouble writing the net ionic equation for LiBr(aq) + AgNO3(aq)

matrix answered on 03/05/07:

LiBr(aq) + AgNO3(aq)

TOTAL IONIC EQUATION
Li+(aq) + Br-(aq) + Ag+(aq) + NO3-(aq)---->Li+(aq) + NO3-(aq) + AgBr(s)

Subtract all ions that are the same on both sides of the arrow.

NET IONIC EQUATION
Br-(aq) + Ag+(aq) ---> AgBr(s)

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Question/Answer
JustinK asked on 03/03/07 - Percent Yield, Please Help!

Given the balanced equation: 2KClO3 --- 2KCl+3O2

If the decomposition of 2.00g of KClO3 gives 0.720 of O2, what is the percent yield for the reaction?

(I dont know how to find the theoretical yield needed in order to solve this problem.)

matrix answered on 03/04/07:

You have 0.0163 moles of KClO3 and it made 0.0225 moles of O2.

From equation 2 moles of KClO3 gives 3 moles of O2.Then 0.0163 moles will give X moles.
2/1.0163 = 3/X
X = 0.0245 moles (Theory)

0.0225/0.0245 x 100 = % yield

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