Ideal Gas Molecules
4 marks · EasyA fixed mass of gas is kept at a constant temperature of 300 K. The initial volume of the gas is 2.0 dm³ at a pressure of 100 kPa. The gas is then compressed to a pressure of 250 kPa.
Name the law that relates the pressure and volume of the gas in this situation.
Calculate the new volume of the gas after compression. Give your answer to two significant figures.
State the assumption made about the temperature in order for this law to apply.
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.
Show answer
(a) Boyle's law
(b) 0.80 dm³ · must show p1V1 = p2V2, V2 = p1V1/p2
(c) The temperature must stay constant. · must show constant temperature
Common mistakes: Forgetting to keep units consistent; Not stating constant temperature
Show mark scheme and worked solution
Marking points
B1 (a) · 1 mark · Correctly states Boyle's law.
M1 (b) · 1 mark · Uses p1V1 = p2V2 and rearranges for V2.
A1 (b) · 1 mark · Substitutes values correctly (100 kPa × 2.0 dm³ / 250 kPa = 0.80 dm³), allows follow-through of method. (follow-through)
B2 (c) · 1 mark · States temperature must be constant for Boyle's law to apply.
Worked solution
a) The law is Boyle's law.
b) Use the equation p1V1 = p2V2:
c) The temperature must remain constant for Boyle's law to apply.