Answer to Question #112656 in Physical Chemistry for Amelie

Question

A student determined the enthalpy change for the reaction:
CuSO4(aq) + Zn(s) → Cu(s) + ZnSO4(aq) She placed 50 cm3 of 0.140 mol dm-3 copper
sulfate solution in a polystyrene cup and recorded the temperature for two minutes before adding an excess of zinc powder. She continued stirring and taking the temperature for a further fifteen minutes to produce the graph on the right.
(i) Determine the temperature increase if there had been no heat lost to the surroundings and hence the enthalpy change for the reaction. (ii) State two assumptions that have been made in order to calculate the answer above from the data given.

Answer 1

We will find the enthalpy using the formula mc$∆T$ which mass times the specific heat capacity times the change in temperature , although here we have taken smaller sample of the reactant but will convert the amount of heat liberated from this amount of reactant to amount of the heat liberated by 1 mole of the reactant

Assumption that were made are

1 No heat is lost to the surrounding

2 100 percent reaction has took place