In a calorimetry calculation, if 50 g of water is heated from 20°C to 30°C with specific heat capacity c = 4.18 J/g°C, what is the energy absorbed?

• A. 2090 J
• B. 1045 J
• C. 5000 J
• D. 1000 J

Answer: (A)

Energy absorbed when heating a substance is given by Q = m c ΔT, where m is mass, c is the specific heat capacity, and ΔT is the temperature change. For this water: m = 50 g, c = 4.18 J/g°C, ΔT = 30°C − 20°C = 10°C. So Q = 50 × 4.18 × 10 = 2090 J. The water absorbs 2090 joules of energy. Quick check: 50 × 4.18 is 209, and 209 × 10 is 2090, which matches. The other options would require different ΔT (or mass or c) than the given values.