x Turn on thread page Beta
 You are Here: Home

# Enthalpy calculations questions watch

1. Can anybody help me to underatand a question on molar enthalpy change please?
Basically, the question is about an experiment to investigate the strength of intermolecular forces between ethyl ethanoate molecules and trichloromethane molecules. 0.10mol of each liquid is mixed in a copper calorimeter (starting temp for both is the same).
Results found are:
Mass of ethyl ethanoate = 8.80g
" " of throchloromethane = 11.95g
Temp. Increase on mixing = 9.5K.

The question asks me to calculate heat required to increase the temperature of each liquid by 9.5K during mixing (which I've done), but then asks me to use those answers to calculate molar enthalpy change in kJ mol-¹ for the mixing process, which is the part I dont understand. How do I do this? I have the equation of ∆H = -q/n but I'm not sure what each bit of this represents, or how to use it. Help would be much appreciated, sorry it's such a long question!
2. (Original post by KLouise99)
Can anybody help me to underatand a question on molar enthalpy change please?
Basically, the question is about an experiment to investigate the strength of intermolecular forces between ethyl ethanoate molecules and trichloromethane molecules. 0.10mol of each liquid is mixed in a copper calorimeter (starting temp for both is the same).
Results found are:
Mass of ethyl ethanoate = 8.80g
" " of throchloromethane = 11.95g
Temp. Increase on mixing = 9.5K.

The question asks me to calculate heat required to increase the temperature of each liquid by 9.5K during mixing (which I've done), but then asks me to use those answers to calculate molar enthalpy change in kJ mol-¹ for the mixing process, which is the part I dont understand. How do I do this? I have the equation of ∆H = -q/n but I'm not sure what each bit of this represents, or how to use it. Help would be much appreciated, sorry it's such a long question!
Imagine that you mix one mole of each together. The energy released is your enthalpy change.

However, you can't work this out without the specific heat capacities of the two liquids
3. (Original post by charco)
Imagine that you mix one mole of each together. The energy released is your enthalpy change.

However, you can't work this out without the specific heat capacities of the two liquids
The question does give me the specific heat capacities, I just didnt include them in this post I dont understand what calculation I need to do though?
4. (Original post by KLouise99)
The question does give me the specific heat capacities, I just didnt include them in this post I dont understand what calculation I need to do though?
If you have calculated the energy change for 0.1 mol of liquid (for example) then you multiply it by 10 to get per mole.

Basically divide the energy change by the number of moles that you have used.

TSR Support Team

We have a brilliant team of more than 60 Support Team members looking after discussions on The Student Room, helping to make it a fun, safe and useful place to hang out.

This forum is supported by:
Updated: November 12, 2015
Today on TSR

### Did he block me?

What should I do?

### Can you do this at Oxford?

Poll

The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE