Question

The amount of 2.00 mol of a solid ionic compound was dissolved in 225 mL of water in an insulated container. The initial temp of water was 20 deg. C and the final temp. was 47.8 deg C. What is the delta heat Dissolution? Assume the heat absorbed by the container is negligible.

Answer 1

heat = q = mass water x specific heat water x (Tfinal-Tinitial).
That is the q/2 mol.

Answer 2

This was a multiple choice question, with possible answers of -13.1 KJ/mol; -6.26 KJ/mol; -27.8 KJ/mol; or -26.2 KJ/mol.

I was confused as to how to set equation but now I'm confused because if I'm doing this right-none of these answers work.
Thanks!

Answer 3

For anyone in the future, this is because you have q=mcat is solving for Joules, so convert that to kJ and divide by 2 to get kJ/mol.

Answer 4

d=m/v

v=225mL=225cm³

d(water)=1g/cm³

m=225g

Q=mcΔT

Q=225 × 4200×(47.8 –20)

Q=225 × 4.2 × 27.8

Q=–26271j/mol

Q=–26.271kj/mol

2mole ==> –26.271kj/mol

1mole==> xkj/mol

x=–13.1355kj/mol