A 100 g block with a specific heat capacity of 0.5 J/g°C experiences a temperature rise of 20°C. How much heat energy is transferred?

A 100 g block with a specific heat capacity of 0.5 J/g°C experiences a temperature rise of 20°C. How much heat energy is transferred?

• A. 1000 J
• B. 200 J
• C. 2000 J
• D. 4000 J

Answer: (A)

Energy transfer as heat depends on how much substance there is, how much energy each gram needs to raise by one degree (specific heat), and how big the temperature change is. The heat added is Q = m c ΔT. Plugging in m = 100 g, c = 0.5 J/g°C, ΔT = 20°C: 0.5 × 20 = 10 J/g, then 10 × 100 = 1000 J. So the heat transferred is 1000 joules. If you use kilograms, you’d use c in J/kg°C, but with grams and J/g°C you get the same result.

Energy transfer as heat depends on how much substance there is, how much energy each gram needs to raise by one degree (specific heat), and how big the temperature change is. The heat added is Q = m c ΔT.

Plugging in m = 100 g, c = 0.5 J/g°C, ΔT = 20°C:

0.5 × 20 = 10 J/g, then 10 × 100 = 1000 J.

So the heat transferred is 1000 joules. If you use kilograms, you’d use c in J/kg°C, but with grams and J/g°C you get the same result.