Specific Heat Capacity Answers

Specific Heat Capacity

Data

Use the following for Specific Heat capacities

Substance	Specific Heat Capacity c	Units
Water	4200	J kg-1 K-1
Copper	380	J kg-1 K-1
Methylated Spirit	2500	J kg-1 K-1
Turpentine	1800	J kg-1 K-1

Notes

• The heat capacity of an object is the heat required to raise the all of the object’s temperature by 1K
• When heating a liquid you have to heat the vessel that it is in as well.
• When an object at high temperature is dropped into a liquid at low temperature there is a net heat flow from the high temperature object to the low temperature object until they are both at the same temperature.
• Unless you state “Ignoring heat losses” in each question you will lose a mark!

1 Find the quantity of heat needed to heat 0.50 kg of copper from 20^oC to 50 °C.              5700J

2 When 0.25 kg of ice are heated from -10 °C to -2 °C the heat supplied is 4200 J. Find the specific heat capacity of ice.                      2100 Jkg^-1K^-1

3 A vessel of heat capacity 30 J K^-1 contains 0.30 kg of water at 10 °C. When heated by a Bunsen burner for 5 min the temperature rises to 90 °C. At what rate does the Bunsen supply heat energy?     344W

4 A piece of iron of mass 0.20 kg is heated to 100 °C and dropped into 0.15 kg of water at 20 °C. If the temperature of the mixture is 30 °C, find a value for the specific heat capacity of iron.     450 Jkg^-1K^-1

5 A piece of iron of mass 0.05 kg is heated in a flame and then quickly transferred to a calorimeter of mass 0.05 kg and specific heat capacity 360 J kg^-1 K^-1 containing 0.18 kg of water at 18 °C. If the temperature of the water rises to 43 °C, find the temperature of the flame. The specific heat capacity of the iron is 450 J kg^-1 K^-1.                 903 ^oC

6 Which would result in the more serious burn if dropped onto your outstretched hand a white-hot spark from a firework, or a lump of red-hot iron? Explain your answer.

The white hot spark has a higher temperature than the lump of iron

The lump of iron has a greater mass than the white hot spark

They both have the same specific heat capacity.

Lump of iron has greater store of heat energy

The rate of heat transfer from the white hot spark will be greater for the spark than the lump of iron.

A greater quantity of heat will be transferred from the iron

Causing more serious skin damage.