Heat · Chapter 5: Heat calculations

Year 11 Science · About 20 minutes with activities · Turn your sound on

Chapter 5 · Heat calculations

How much energy?1.2 kg of water, 15°C → 100°C

1 kg of waterneeds 4200 J to warm by 1°C

1 kg of metalneeds much less energy for 1°C

WaterL(melting) = 334 000 J/kg · L(boiling) = 2 260 000 J/kg

Melt 0.5 kg of ice at 0°CQ = mL = 0.5 × 334 000 = 167 000 J

Chapter 5 recap

Specific heat capacity: the amount of thermal energy required to raise the temperature of 1 kg of a substance by 1°C. Water: 4200 J kg⁻¹ °C⁻¹.
Q = mcΔT when the temperature changes (ΔT = final − initial; negative means heat lost). Rearrange: m = Q ÷ (cΔT), ΔT = Q ÷ (mc).
Q = mL during a change of state (temperature constant). P = Q ÷ t: power in watts (J per second).
You’ve finished the Heat course. Revise any chapter from the home page

How much energy does it take to boil a kettle?

Chapter 5 · About 20 minutes · sound on

0:00

Voice In Chrome this uses Google’s voice; other browsers use the recorded voice. Your choice here is remembered.