Heating experiments and Q = mcΔT · seed 1 · A4, ink-friendly. The answer key prints on its own page for grown-ups.

Heating experiments and Q = mcΔT

Science · Energy · ages 12-13
Name ______________________   Date ____________

  1. What do you use to measure temperature during a heating experiment?

    • A stopwatch
    • A thermometer
    • A ruler

  2. In a heating experiment, some energy is always lost to the surroundings.

    Circle one:   True   False

  3. What does the 'm' stand for in Q = mcΔT?

    • Minutes
    • Mass
    • Maximum temperature

  4. In a heating experiment 200 g of water (c = 4.18 J/g°C) is heated from 18 °C to 28 °C. How many joules of energy were transferred to the water?

    Answer: ______________

  5. Which change would reduce heat loss to the surroundings in a heating experiment?

    • Using a lid on the beaker
    • Heating for a longer time
    • Using a bigger beaker

  6. If a beaker of water loses heat to the surroundings the temperature rise will be less than predicted by Q = mcΔT using only the heater power.

    Circle one:   True   False

  7. A 50 g metal block absorbs 1500 J of energy and its temperature rises by 15 °C. What is its specific heat capacity in J/g°C?

    Answer: ______________

  8. A student heats 0.5 kg of water. Its specific heat capacity is 4200 J/kg°C. The temperature rises by 10°C. Calculate Q in joules.

    Answer: ______________

  9. Priya starts at 22°C and finishes at 45°C, but she uses ΔT = 45°C in her Q = mcΔT calculation. What mistake did she make?

    • She used the wrong mass
    • She used the wrong specific heat capacity
    • She used the final temperature instead of the change in temperature

  10. A temperature-time graph shows the temperature rising from 20°C to 50°C over 10 minutes at a steady rate. What is the temperature increase per minute, in °C?

    Answer: ______________

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Answer key

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Heating experiments and Q = mcΔT W1-mt_DI1cyAyGyN-s1

  1. A thermometer · A thermometer measures temperature. A stopwatch measures time.
  2. True · Heat escapes into the air and the container, so not all the energy ends up heating the substance.
  3. Mass · m is the mass of the substance being heated.
  4. 8360 · Use Q = mcΔT. m = 200 g, c = 4.18 J/g°C, ΔT = 10 °C. 200 × 4.18 × 10 = 8360 J.
  5. Using a lid on the beaker · A lid stops heat escaping into the air above the water.
  6. True · Heat losses mean not all heater energy goes into the water. Some escapes to the air. The actual temperature rise is smaller.
  7. 2 · Rearrange Q = mcΔT to c = Q / (mΔT) = 1500 / (50 × 15) = 1500 / 750 = 2.0 J/g°C.
  8. 21000 · Q = mcΔT = 0.5 x 4200 x 10 = 21,000 J.
  9. She used the final temperature instead of the change in temperature · ΔT should be 45°C - 22°C = 23°C, not just the final reading.
  10. 3 · The gradient is the rise divided by the time: (50 - 20) / 10 = 3°C per minute.
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