Question

The mass of water in each cup is 200 g. Calculate the energy, in joules, transferred from the water in a cup when the temperature of the water falls by 8°C. Specific heat capacity of water = 4200 J / kg°C

Answer 1

Given:

The mass of water in each cup is 200 g. Temperature of water in cup falls by 8°C.

To find:

Energy transferred from the cup?

Calculation:

• Let mass be m , specific heat capacity be c and temperature difference be $\Delta\theta$.

Applying the PRINCIPLE OF CALORIMETRY:

$\therefore \: H = m \times c \times \Delta \theta$

$\implies\: H = \dfrac{200}{1000} \times 4200 \times 8$

$\implies\: H = 0.2\times 4200 \times 8$

$\implies\: H = 6720 \: joule$

$\implies\: H = 6.72\: kilojoule$

• So, heat transferred is 6.72 kJ.

Since the temperature of water falls by 8°C, we can say : 6.72 kJ energy was released from the cup.