Question

When a sample of aluminium of unknown mass was subjected to 1.8 kJ of heat, the temperature of the aluminium sample increased from 26°C to 31°C. What was the mass of the sample? (specific heat of Al = 0.90 J/g°C)

• A. 200 g
• B. 400 g
• C. 600 g
• D. 800 g

Hint:

To calculate the mass of a sample when given heat energy, specific heat, and temperature change, use the formula \( Q = m c \Delta T \), where \( Q \) is the heat energy in joules, \( m \) is the mass in grams, and \( c \) is the specific heat in J/g°C.

Answer 1

The Correct Option is B

We can use the formula for heat absorbed or released: \[ Q = m c \Delta T \] where: - \( Q = 1800 \, \text{J} \) (heat energy), - \( m \) is the mass of the aluminium, - \( c = 0.90 \, \text{J/g°C} \) (specific heat capacity of aluminium), - \( \Delta T = 31°C - 26°C = 5°C \). Rearranging the formula to find the mass: \[ m = \frac{Q}{c \Delta T} = \frac{1800}{0.90 \times 5} = \frac{1800}{4.5} = 400 \, \text{g} \] Thus, the mass of the sample is 400 g.