# Thermodynamics chemical reaction problem

1. Sep 8, 2007

### Benzoate

1. The problem statement, all variables and given/known data
What are q and w (in kJ) for the reaction of 22 g of Na(s) and 82 g of Cl2(g) to produce NaCl at 1 atm and 298 K.

2. Relevant equations

w=-delta(n(g))* R*T where delta(n(g)) = the moles of gas created during the reaction

3. The attempt at a solution

First, I wrote the chemical reaction for Na and Cl2

2Na(s) +Cl2(g)=> 2NaCl

delta(n(g))=0-1 = -1

82 g Cl2*(1 mol Cl2/70.98 g Cl2)*(-1 mol gas/1mol Cl2)= -1.16

delta n(g) =-1.16
w=-delta(n(g))*RT=(-1.16)(8.314)(298 K)=2.87 kJ

But thats not the answer according to the back of my textbook.

2. Sep 9, 2007

### Staff: Mentor

The volume is changing from the volume of Cl2 gas to essentially zero.

Can one apply w = p $\Delta{V}$? 1 mole of gas has a volume of 22.4 l.

Then there is the heat.

Last edited: Sep 9, 2007