Practical: investigate the specific heat capacity of a substance
4 marks · NormalA student wants to find the specific heat capacity of water using an electric immersion heater.
Describe how the student could carry out this experiment. You may refer to apparatus, measurements, and calculations. List at least three key steps.
State one precaution the student should take to improve the accuracy of the result.
Explain why a lid is used on the beaker during the experiment.
Work this out on paper, then compare with the answer and worked solution below. With a free account you can submit written answers for marking.
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(a) 1. Measure a known mass of water into a beaker using scales. 2. Record the initial temperature with a thermometer. 3. Insert an electric immersion heater and supply power for a measured time (take V, I, t). 4. Record the final temperature and calculate the temperature rise. 5. Calculate the energy supplied and use .
(b) Use insulation around the beaker, or stir the water for even heating.
(c) To reduce heat loss to the surroundings.
Common mistakes: Missing key step; Not mentioning mass or temperature measurement; Not including reason for lid
Show mark scheme and worked solution
Marking points
M1 (a) · 1 mark · States or describes correct measurement of mass, initial and final temperature, energy supplied (via V, I, t), and/or calculation step. (Any three valid steps required for 2 marks.)
M2 (a) · 1 mark · Includes use of calculation: either Q = V I t, or c = Q/m Δθ, or combining all steps clearly.
B1 (b) · 1 mark · States a relevant precaution (e.g. insulation, lid, stirring for even temperature, calibrated thermometer).
B2 (c) · 1 mark · Correctly explains the function of the lid (to reduce heat loss).
Worked solution
a) To investigate the specific heat capacity of water: - Measure a known mass (e.g. 200 g) of water into a beaker using scales. - Record the initial temperature with a thermometer. - Place an electric immersion heater in the water. - Connect the heater to a power supply and measure the voltage (V), current (I), and heating time (t). - After heating, record the final temperature of the water. - Calculate the temperature change and the energy transferred: Q = V × I × t. - Calculate c using c = Q / (m Δθ).
b) Precaution: Use insulation around the beaker, or stir continuously for uniform heating.
c) A lid is used on the beaker to reduce unwanted heat loss to the surroundings from evaporation and convection.