03 The Gaseous State, Set A To print: Ctrl + P, paper A4, margins Default.
Learners' AlleyDesigned by Khow Willard
03
The Gaseous State
Set AFoundations
Name
Time 1 hour
Total 40 marks
Data: R = 8.31 J mol−1 K−1, 1 atm = 101 325 Pa, L = 6.02 × 1023 mol−1, Ar: H 1.0,C 12.0,O 16.0.
A
From the lesson
13 marks
1
Convert each quantity into S.I. units.
(a)
25 °C
[1]
(b)
250 cm3
[1]
(c)
2.00 atm
[1]
Source: Learners' Alley, The Gaseous State slides
2
A 2.00 dm3 sample of gas at 27 °C is heated to 127 °C at constant pressure.
(a)
Calculate the new volume of the gas.
[2]
(b)
Explain why the new volume is not 2.00 × 127 ÷ 27 = 9.41 dm3.
[1]
Source: Learners' Alley, The Gaseous State slides
3
Common0.320 g of a gas occupies 246 cm3 at 1.00 × 105 Pa and 23 °C. Calculate the Mr of the gas and suggest its identity.
[2]
Source: Learners' Alley, The Gaseous State slides
4
2.00 dm3 of a gas at 27 °C and 100 kPa is compressed to 0.500 dm3 and heated to 127 °C. Calculate the final pressure of the gas.
[2]
Source: Learners' Alley, The Gaseous State slides
5
Dry air is 78% N2, 21% O2 and 1% Ar by amount. Calculate the partial pressure of O2 when the total pressure is 101 kPa.
[1]
Source: Learners' Alley, The Gaseous State slides
6
CommonWhich gas deviates more from ideal behaviour, NH3 or CH4? Explain your answer.
[2]
Source: Learners' Alley, The Gaseous State slides
B
Practice
27 marks
7
A small spacecraft of capacity 10 m3 is connected to another of capacity 30 m3. Before connection, the pressure inside the smaller craft is 50 kPa and the pressure inside the larger craft is 100 kPa. All measurements are made at the same temperature.
What is the pressure in the combined spacecraft after connection?
A75 kPa
B87.5 kPa
C100 kPa
D125 kPa
E150 kPa
Answer [1]
Source: N90/1/5, via EJC 2022 JC1 Gaseous State Tutorial, A1
8
Deuterium, 2H, is an isotope of hydrogen. A 2 g sample of hydrogen, H2, at temperature T and volume V exerts a pressure p.
Which of the following would also exert a pressure p at the same temperature T?
A2 g of deuterium, D2, in volume V
B4 g of deuterium, D2, in volume V/2
Ca mixture of 1 g of H2 and 2 g of D2 in a total volume V
Da mixture of 2 g of H2 and 1 g of D2 in a total volume 2V
Answer [1]
Source: J98/3/8, via EJC 2022 JC1 Gaseous State Tutorial, A6
9
A vessel contains 120 g of oxygen at a pressure of 3.00 atm at 25 °C.
(a)
5.00 g of hydrogen is added at the same temperature, without changing the volume of the vessel. Calculate the final pressure.
[2]
(b)
The mixture is then exploded and allowed to cool back to 25 °C. Calculate the pressure of the gas in the vessel.
[2]
Source: RJC 2010/11 Gaseous State Tutorial, Q8
10
CommonUnder what conditions of temperature and pressure do real gases behave most like ideal gases? Give reasons for your answers.
A gaseous hydrocarbon A contains 85.7% carbon by mass. When 10.0 cm3 of A underwent complete combustion in 80.0 cm3 of oxygen, the remaining gases occupied 65.0 cm3. After shaking these gases with aqueous sodium hydroxide, 35.0 cm3 of gas remained. All volumes were measured at room temperature and pressure. Determine the empirical and molecular formulae of A.
CommonArrange these gases in order of increasing deviation from ideal behaviour. Explain your order.
He Ne O2 H2O NH3 C2H6
[3]
Source: RJC 2010/11 Gaseous State Tutorial, Q7(b)
14
CommonThe graph shows pV against p for Ne, O2 and NH3 at the same temperature.
(a)
Explain why the three lines meet at zero pressure.
[1]
(b)
Explain why pV decreases with increasing pressure for O2 and NH3 but increases for Ne.
[3]
Source: RJC 2010/11 Gaseous State Tutorial, Q7(c)
15
ChallengeAt sea level, an inflated bicycle tyre contains 670 cm3 of air at an internal pressure of 6.00 bar and 20 °C. The tyre is marked "maximum internal pressure 8 bar". Atmospheric pressure at sea level is 1.01 bar. The tyre bursts if the difference between the internal and external pressures becomes too great.
(a)
Use the ideal gas equation to calculate the amount of air in the tyre at sea level. (1 bar = 1.00 × 105 Pa)
[2]
(b)
The bicycle is carried in the luggage hold of an aircraft at a height of 10 000 m, where the temperature is 5 °C and the pressure is 0.28 bar. The volume of the tyre does not change. Calculate the pressure inside the tyre in the hold.
[2]
(c)
Some airlines insist that bicycle tyres are let down before a flight. Should this tyre be let down? Use your answer to (b) to justify your answer.