A student carried out the following reaction in a coffee cup calorimeter:

Question

A student carried out the following reaction in a coffee cup calorimeter: 

CaO +2HCl → H2O +CaCl2

She used 4.7 g of reactant and 155.5 g of acid. The initial temperature of the system was 23.8°C and the final temperature was 30.8°C . Assuming the specific heat capacity of the solution is 4.18 J/g°C, calculate the total energy released or absorbed by the system in J, rounded to the nearest whole number. 

Answer 1

q = mC∆T

q = heat energy?

m = mass = 4.7 g + 155.5 g = 160.2 g

C = specific heat = 4.18 J/gºC

∆T = change in temperature = 30.8 - 23.8 = 7.0ºC

Solve for q and the sign will be negative (-) because the temperature of the surroundings increased indicating an exothermic reaction.