Specifc Heat

Question 1

How much thermal energy is required to heat
the following items from 30°C to 120°C?
a 2.0 kg steel barbeque plate
b $2 coin of mass 6.6 g (specific heat
capacity = 380 J kg–1 K–1

Answer 1

a Q = mc∆T
= 2.0 × 460 × (120 − 30 )
= 82 800 J
= 83 000 J (2 sf)

b Q = mc∆T
= _____ 6.6
1000 × 380 × (120 − 30 )
= 226 J
= 230 J (2 sf)
(Note: to convert g to kg, divide by 1000.

Question 2

How much heat energy is required to
bring a saucepan containing 500 mL
of water at 20°C to boiling point?
(1 L of water has a mass of 1 kg.

Answer 2

Q = mc∆T
= 0.500 × 4180 × (100 − 20)
= 1.67 × 105 J
= 1.7 × 105 J (2 sf)

Question 3

A 70.0 g copper block at a temperature of 80.0°C is placed in contact with another copper
block of the same mass at a temperature of 20.0°C. Calculate the final temperature when
the blocks have reached thermal equilibrium.

Answer 3

50

Question 4

50 mL (0.050 kg) of hot water at 80°C is mixed with 150 mL of cold water at 5°C. Calculate
the final temperature when thermal equilibrium is reached.

Answer 4

24° C

Question 5

A 20 g stainless steel spoon at room temperature (20°C) is placed in 200 mL of coffee
at 70°C in a foam cup. Assume the foam cup doesn’t absorb any energy. Calculate the
temperature when thermal equilibrium is established. The specific heat capacity of
stainless steel is 500 J kg–1K–1.

Answer 5

70° C