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# Enthalpy change help please? watch

1. i'm really confused how to do this, and i know this list may seem big, but whatever help you can offer me with these problems i'd be ever so greatful. thanks!

1. 0.74g (0.010 mol) of propanoic acid was burned in a simple calorimeter. The temperature of 200g of water rose by 8.0K. What value does this give for the enthalpy of combustion of propanoic acid?

2. 50cm^3 of 2.00mol dm -^3 sodium hydroxide and 50.0 cm^3 of 2.00mol dm-^3 hydrochloric acid were mixed in an expanded polystyrene beaker. The temperature rose by 11.0K.
a) calculate ΔH for the reaction.
b) how will this value compare with the accepted value for this reaction.
c) explain the answer to part b?

4. 0.46g(0.010 mol) of ethanol was burnt in a simple calorimeter containing 100g of water. The temperature rose by 24.0K What is the enthalpy change of combustion of ethanol?

5. In an experiment using a simple calorimeter, 8.00g of ammonium nitrate (NH4NO3) was dissolved in 50.0g of water. The temperature fell by 10.1 deg C. Calculate the enthalpy change for this process. Specific heat capacity of water is 4.18JK^-1g^-1. The specific heat capacity of the container can be ignored.

6. An experiment was carried out to determine the value for the enthalpy of the combustion of liquid hexane. Burning 1.75g of hexane caused the temperature of 250g of water to rise by 78 deg C. Use the infromation to calculate a value for the enthalpy of combustion of hexane. Specific heat capacity of water is 4.18JK^-1g^-1. The specific heat capacity of the container can be ignored.

7. Calculate the amount of heat energy needed to increase the temperature of 150g of water from 20°C to 35°C
2. E = mcDT
3. (Original post by boromir9111)
E = mcDT
Thank you! any idea for any of the other questions? if not no worries.
4. (Original post by Lalanita)
Thank you! any idea for any of the other questions? if not no worries.
Pretty much all the questions involve, at some stage, the equation
delta U = mc delta T
5. yep, all of them involve it that's why i didn't put any question number next to the formula

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