A beaker contains 0.500 kg of water at a temperature of 3.0 °C. The beaker is heated, and the
internal energy of the water increases by 21.0 kJ.
The specific heat capacity of water is 4200 J / (kg °C).
What is the temperature of the water after it has been heated?

The temperature of the water after it has been heated is 13°C

Explanation:

Heat capacity H is expressed as shown :

H = mc∆t

H is the internal energy of the water

m is the mass of the water

c is the specific heat capacity of the water

∆t is the change temperature

Given H = 21kJ = 21,000Joules

m = 0.500kg

c = 4200 J / (kg °C).

∆t = t2-t1

t2 is the final temperature

t1 is the initial temperature = 3°C

Substituting the parameters;

21000 = 0.5(4200)(t2- 3)

21000 = 2100(t2-3)

21000 = 2100t2 - 6300

2100t2 = 21000+6300

2100t2 = 27300

t2= 27300/2100

t2 = 13°C