Question

Two hundred grams of a substance requires 9.76 kj of heat to raise its temperature from 25degrees C to 45 degrees C

Answer 1

Heat can be calculated using the formula:

U = mCpΔT

where:

U = internal energy or heat
m = mass of substance
Cp = specific heat capacity of a substance (constant)
ΔT = change in temperature = (Tf - Ti)

In the problem, we are given all these terms except for the Cp, which can help identify what the substance is. This is because Cp is unique and constant for a particular substance.

9760 = 200(Cp)(45-25)
Cp = 2.44 J/g-°C

Now, look for a library or list of specific heat capacities. Look for a substance that has the closest value to what you calculated. Based on data, the substance used is ethyl alcohol which has a Cp of exactly 2.44 J/g-°C

You can use this as reference: http://www.engineeringtoolbox.com/specific-heat-capacity-d_391.html