Gases

Question 1

(1) Which Kinetic E. to Temp graph shows the way in which the average kinetic energy of the molecules of a gas changes with temperature?

Answer 1

K |       /
E |     /
    |   /
    | /
    |
    |\_\_\_\_\_\_\_\_\_\_\_\_
       TEMP

Question 2

(2) The air molecules in the cylinder move randomly. Describe how they exert a pressure on the cylinder.

Answer 2

• collisions (1)

* with (walls of) cylinder (1)

Question 3

(2) The cylinder contains air at a pressure of 21 000 kPa. The volume of air in the cylinder is 15.0 litres. The temperature of the air does not change. Show that the new volume of air is about 3 200 litres.

Answer 3

V = 15.0 × 21 000  (1) 
            100 
3 150(litres)(1)

Question 4

(3) The cylinder is filled with air in a hot country and then taken to a cold country. The temperature in the hot country is 305 K. The temperature in the cold country is 278 K. The pressure in the cylinder in the hot country is 21 000 kPa. Calculate the pressure in the cylinder in the cold country.

Answer 4

21 000 (× V)  = P (× V) (1)
     305            278 
volume same (1) 
19 100 (kPa) (1)