Homework Help: Gas Stoichiometry

1. Nov 7, 2009

blstrs

1. The problem statement, all variables and given/known data

Calcium carbide reacts with water to produce acetylene gas: CaC2 (s) + 2H2O (l) >> Ca(OH)2 (aq) + C2H2 (g). What volume of wet acetylene is collected at 25C and 715 torr when 5.20g CaC2 is reacted with an excess of water? (Vapor pressure of water at 25C = 23.8 torr)

2. Relevant equations

PV=nRT
P(total)=P1+P2...etc

3. The attempt at a solution

I found the moles of "dry" C2H2 (.0811 mol). However, I'm not very sure where vapor pressure and the "wet" comes in...

2. Nov 7, 2009

Bohrok

What is the total pressure, Ptotal, of the system? What are the partial pressures?

3. Nov 7, 2009

blstrs

Ptotal=715 torr
PH2O=23.8 torr
PC2H2=691.2 torr

I'm still not exactly sure how all of these fit in....

4. Nov 8, 2009

Staff: Mentor

What is volume of acetylene calculated using its partial pressure?

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methods

5. Nov 18, 2009

_Molly_

Using the equation PV = nRT, do you recall what P, V, n, R and T stand for? They also need to be in certain units. This may or may not require converting. Do you still need help for this?