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Chemistry Forums for Students => High School Chemistry Forum => Topic started by: Ter on December 18, 2012, 10:51:15 AM

Title: Molar Volume
Post by: Ter on December 18, 2012, 10:51:15 AM
Hi I was wondering when to apply the molar volume for gases where you can determine the volume of a gas in a reaction given the stoichiometric coefficients of every reactant and product.


I am not sure if the following is correct, I know how I allocate A, B, C and D as the different states of matter may be wrong in terms of reaction but they are examples. Please correct me if I'm wrong.

Say
A+B->C+D

Scenario 1: I know if A, B, C, D are gases, I can use the molar volume to determine the volume of any of their gases.

Scenario 2: If A is a solid, B is a liquid and C and D are gases, if I want to find out how much A is needed to form a particular quantity of D ( maybe 3g ), then since A is not a gas, I will have to use the molar calculation method, by finding no of moles and equating  then multiplying by the molar mass of A etc. I cannot use the molar volume method, simply because not all of the elements I am 'comparing' are not in gaseous state.

Scenario 3: If A is a solid,  B is a gas and C is a liquid and D is a gas, if I want to find out how much B is needed to form a particular quantity of D ( maybe 3g ), then can I use the molar volume method? I'm not sure as the reaction is not all gases..

I really need to understand this.

Thank you so much!
Thanks in advance,
J
Title: Re: Molar Volume
Post by: Hunter2 on December 18, 2012, 11:50:41 AM
At least all components are connected over the moles.

A + B => C + D

So you can calculate each of them. The molar Volume you can use if it is a gas. In all other cases you have to go over the molar mass.

Or what is your question?

Title: Re: Molar Volume
Post by: Ter on December 18, 2012, 10:01:06 PM
Thanks, sorry I wasn't clear.

 I know that I can use the molar volume if it is a gas. But if let's say I want to know how much of solid A is formed from gas B, can I still use molar volume since A is not a gas?

If I want to know how much of gas A is formed from gas B and the other elements involved in the reaction are in the solid and aqueous state, can I still use molar volume since not every element in the equation is a gas?
Title: Re: Molar Volume
Post by: Hunter2 on December 19, 2012, 12:47:27 AM
Yes you can use. You convert the Volume to mole and then you get the moles of your solid as well.