## Thermal expansion

**1 Write the following in order of increasing expansion: liquid, gas, solid.**

**2 Write down three examples of the expansion of a solids.**

**3 Give two reasons why mercury is used in thermometers.**

**4 Why is alcohol used in some thermometers?**

**5 (a)What is a bi-metallic strip?**

**Aluminium expands more than**

**copper.**

**(b) what wil happen when it is put in a freezer?**

**6 What happens to the volume of a sample of water when it is frozen?**

**7 What would you expect the temperature at the bottom of a pond to be if the water at the top of the pond had frozen?**

**8 (a) a metal washer is heated. What happens to the hole in the centre of the washer?**

**(b) What would happen if the piston and cylinder in a car engine were made of metals that expanded by different amounts when heated?**

**9 What would be the approximate increase in length of a 100 cm long iron rod if it is heated by 50**

^{0}C?**10 Glass is a poor conductor of heat. Why will a hot, thick glass beaker break if put gently but quickly into cold water? Suggest why this does not happen if the beaker is made of:**

**(a) aluminium;**

**(b) Pyrex glass.**

**11 The air in a closed cylinder at a pressure of 50 000 Pa and at 27**

^{o}C is heated to 227^{0}C. What is its new pressure?**12 The absolute temperature of the gas in a closed cylinder is reduced to ½ of the original value. What happens to its pressure?**

**13 A fixed mass of gas has a volume of 4 m**

^{3 }at 27^{0}C and at a pressure of 150 000 Pa. The pressure is now reduced to 100 000 Pa and the volume is decreased at the same time to 0.5 m^{3}. What is the final temperature of the gas?**14 If the temperature of a gas is raised, what happens to the pressure of the gas if its volume stays the same?**

**15 What is meant by absolute zero?**

**16 What is the value of absolute zero?**

**17 What is:**

**(a) 0**

^{0}C in K; (b)*100*^{o}in K?**18 If 4litres of gas at 27**

^{o}C are heated to 127^{0}C at a constant pressure, what will be the new volume of the gas?**19 What happens to the pressure of the air in a car tyre during a long journey on a hot day?**

**20 Draw a graph to show:**

**(a) how the volume of a gas changes if it is heated at a constant pressure**

**(b) how the pressure of a gas changes if it is heated at constant volume**

**(c)**

**how the pressure of a gas changes if it is expanded at a constant temperature**