What can the chemist report for the specific heat capacity of the substance?

Question

A chemist carefully measures the amount of heat needed to raise the temperature of a 754.0g sample of a pure substance from 2.1°C to 20.2°C.

The experiment shows that 9.69kJ of heat are needed. 

What can the chemist report for the specific heat capacity of the substance?

Be sure your answer has the correct number of significant digits.

Answer 1

As in previous questions on the same topic, you use the formula q = mC∆T

q = heat = 9.69 kJ

m = mass = 754.0 g

C = specific heat = ?

∆T = change in temperature = 20.2º - 2.1º = 18.1º

Solving for C we have...

C = q/(m)∆T) = 9.69 kJ/(754.0 g)(18.1º)

C = 0.000710 kJ/gº = 0.710 J/gº (3 sig. figs.) (or since 2.1º has only 2 s.f., you might report it as 0.71 J/gº)