Six molecules are travelling with the directions and speeds shown in the diagram below.

What is the rootāmeanāsquareāspeed of these molecules?
283 m sā1
342 m sā1
685 m sā1
831m sā1
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Molecular Kinetic Theory Model
Six molecules are travelling with the directions and speeds shown in the diagram below.
What is the rootāmeanāsquareāspeed of these molecules?
283 m sā1
342 m sā1
685 m sā1
831m sā1
Choose your answer
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The average mass of an air molecule is 4.2 Ć 10ā26 kg
What is the mean square speed of an air molecule at 850 K?
647 m2 sā2
743 m2 sā2
4.19 Ć 105 m2 sā2
8.38Ć 105 m2 sā2
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The equation for the kinetic theory model, pV =Nm(crms)2 is given on the data and formula sheet.Ā
Which of the following statements is not a valid assumption when deriving this equation?
The collisions between gas molecules and the walls of a container are inelastic
Attractive forces between molecules are negligible
The duration of a collision is negligible compared with the time between collisions
The volume of the molecules is negligible compared with the volume of the gas
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Pollen grains are placed in a transparent illuminated box and water is added.Ā The pollen grains are seen to move randomly on the surface of the water when viewed with a microscope.Ā
What is the cause of the random motion of the pollen grains?
The pollen grains are moving randomly due to their temperature
The pollen grains are moving due to convection currents caused by the water being heated by the light
The pollen grains absorb light energy and gain kinetic energy
The pollen grains collide with the water molecules
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The equation for the kinetic energy of a gas molecule is given below:Ā
Ā Ā Ā Ā Ā Ā Ā Ā Ā m
Ā =
kT
What does Ā represent?
The sum of the squares of the speeds of the gas molecules
The average of the square of the speeds of the gas molecules
The average speed of the gas moleculesĀ
The rootāmeanāsquare speed of the gas molecules
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The gas argon has a density of 1.80 kg mā3.Ā When it is at a temperature of 350 K it exerts a pressure of 1.00 Ć 105 Pa.Ā
What is the rootāmeanāsquare speed of argon molecules?
224 m sā1
408 m sā1
671 m sā1
1340 m sā1
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What is the total internal energy of 3.2 mol of an ideal gas which has a temperature of 25āÆĀ°C?
1000 J
7200 J
8000 J
12 000 J
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Which of the graphs below shows the correct relationship between the mean square speed of a molecule in a gas, Ā , and its temperature in degrees Celsius?
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A sample of air contains oxygen, and nitrogen molecules.Ā An oxygen molecule is heavier than a nitrogen molecule.Ā
Which row in the table below correctly compares the magnitude of the kinetic energy and meanāsquare speed of the oxygen and nitrogen molecules?Ā
Ā | Magnitude of kinetic energy of oxygen and nitrogen molecules | Magnitude of meanāsquare speed of oxygen and nitrogen molecules |
A B C D | equal equal not equal not equal | equal not equal equal not equal |
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An ideal gas is initially at a temperature of 500°C.Ā It is heated so that the root mean square velocity of the gas molecules is doubled.Ā
What are the values for the temperature of the gas and the mean kinetic energy of the gas molecules after the gas has been heated?
 | Temperature /°C | Kinetic Energy /J |
A B C D | 1273 1546 2819 3092 | 3.20 Ć 10ā20 3.20 Ć 10ā20 6.40 Ć 10ā20 6.40 Ć 10ā20 |
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The diagram below shows a single molecule of mass 4.6 Ć 10ā26 kg moving with a speed of 500 m sā1 in a rigid cubical container.Ā The length of the side of the container is 0.25 m.Ā
What is the average pressure exerted on the wall by the molecule?
You may assume that the collisions between the molecule and the walls are perfectly elastic.
3.7 Ć 10ā25 Pa
7.4 Ć 10ā25 Pa
3.7 Ć 10ā19 Pa
7.4 Ć 10ā19 Pa
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Air can be taken to consist of 80% nitrogen molecules and 20% oxygen molecules.Ā Nitrogen has a relative molecular mass of 28 and oxygen has a relative molecular mass of 32.Ā
What is the ratio of the root mean square speed of nitrogen molecules to that of oxygen molecules in the air?
0.25
0.50
1.07
1.20
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On a day when the atmospheric pressure is 102 kPa and the temperature is 10°C, the pressure in a car tyre is 190 kPa above atmospheric pressure.Ā After a long journey the temperature of the air in the tyre rises to 30 °C.Ā
What is the percentage increase in the rootāmeanāsquare speed of the molecules of air as a result of this journey ?Ā
Assume that no air is lost from the tyres.
3.5 %
96.5 %
103.5 %
107 %
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A gas in a sealed container with a fixed volume has a pressure. Its particles have a root mean square speed
of
. The gas is cooled until it has a pressure
.
What is the root mean square speed of the gas particles after cooling?
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