## Problem 4.17

Brian_Ho_2B
Posts: 221
Joined: Fri Aug 09, 2019 12:16 am

### Problem 4.17

I'm looking at problem 4.17, where in part e, it asks for the change in enthalpy. The information given is that we have 2SO2 + O2 produces 2SO3 (all gasses) at 25 degrees C and 1.00 atm. I know that the work done is positive 40J, but I have no idea how to find change in enthalpy for this problem. Can anyone point me in the right direction?

Julie Park 1G
Posts: 100
Joined: Thu Jul 25, 2019 12:15 am

### Re: Problem 4.17

You'll want to use the standard enthalpies of formation and the coefficients of the balanced equation to find the enthalpy of the reaction.

$\Delta H = 2(-395.72kJ\cdot mol^-1)-2(-296.83kJ\cdot mol^-1)=-197.78kJ\cdot mol^-1$

Since the question says that 0.030mol of SO2 are consumed, you can use dimensional analysis by multiplying 0.030 mol of SO2 by the ratio of -197.78 kJ per 2 mols of SO2 to find the final value, which you can convert from kJ to J.

Brian_Ho_2B
Posts: 221
Joined: Fri Aug 09, 2019 12:16 am

### Re: Problem 4.17

Julie Park 1G wrote:You'll want to use the standard enthalpies of formation and the coefficients of the balanced equation to find the enthalpy of the reaction.

$\Delta H = 2(-395.72kJ\cdot mol^-1)-2(-296.83kJ\cdot mol^-1)=-197.78kJ\cdot mol^-1$

Since the question says that 0.030mol of SO2 are consumed, you can use dimensional analysis by multiplying 0.030 mol of SO2 by the ratio of -197.78 kJ per 2 mols of SO2 to find the final value, which you can convert from kJ to J.

Thank you; I couldn't find those values for those molecules in the book anywhere so I tried other ways of finding the delta H. Turns out we had to look them up online.

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