particle model of matter - particle motion in gases

Question 1

how do particles in a gas move

Answer 1

with random direction and speed
- far away from each other

Question 2

how does the temperature of a gas relate to the average energy

Answer 2

the higher the temperature, the higher the average kinetic energy

Question 3

what happens when gas particles move at a high speed

Answer 3

• they bang into each other and exert a force
• faster particles means more frequent collisions

Question 4

what factors increase / decrease gas pressure in a container

Answer 4

• increasing temperature will increase the speed, and so the pressure ( if volume is kept constant )
• if temperature is constant, increasing volume means particles get more spread out and will hit container walls less often, decreasing pressure

Question 5

what is the relationship between volume and pressure

Answer 5

they are inversely proportional, increasing volume decreases pressure, decreasing volume increases pressure

Question 6

what is the equation for pressure and volume for a gas of a fixed mass at a constant temperature

Answer 6

pV = constant p= pascals ( Pa ) v = volume ( m ^ 3 )

Question 7

equation for change in momentum

Answer 7

The change in momentum is equal to the force multiplied by time. It is also the same as impulse

Question 8

how to find pressure

Answer 8

force/ area

Question 9

how does the speed of particles in a gas differ from ones in a solid or liquid

Answer 9

they are quicker than ones in a solid or liquid

Question 10

what happens if you increase the volume of a gas in a container

Answer 10

increasing the volume in which a gas is contained, at constant
temperature, can lead to a decrease in pressure.

Question 11

Describe gas particles in a container

Answer 11

Since the particles in a gas are moving fast and randomly, collisions occur frequently. These collisions may be between two particles, between a particle and the wall of the container, or between a particle and something else in the container.

For example, the collisions caused by a gas trapped inside a balloon cause forces to act outwards in all directions, giving the balloon its shape.

Question 12

why might the pressure of gas molecules increase

Answer 12

The pressure from gas molecules may increase if there are more molecules colliding each second or if the molecules are moving faster.

Question 13

what happens if the volume of gases inside a container stays the same

Answer 13

the pressure of a gas increases as its temperature increases. (directly proprtional)

Question 14

If the temperature of a gas stays the same, the pressure of the gas increases as the volume of its container decreases…why?

Answer 14

This is because the same number of particles collides with the walls of the container more frequently as there is less space. However, the particles still collide with the same amount of force.

Question 15

what is work

Answer 15

the transfer of energy by a force

Question 16

what happens when you do work on a gas

Answer 16

Doing work on a gas increases the internal energy of the gas and can cause an increase in the temperature of the gas.

Question 17

work done equation

Answer 17

force x distance

Question 17

work done equation

Answer 17

force x distance

Question 18

what does mechanical work do

Answer 18

transfers energy from the person or machine’s store of chemical energy to the internal energy store of the gas.

Question 19

why does a bicycle pump get warm when its used to inflate a tyre

Answer 19

Since the volume of the gas has decreased, the pressure increases because the particles are moving in less space and collide more often. The temperature of the gas is not fixed in most applications and the increased pressure leads to an increase in temperature. This is because the temperature is a measure of the average kinetic energy of particles - the increase in the internal energy of the gas means that the temperature must increase.

Question 20

what is the pressure of a gas due to

Answer 20

the particle’s colliding with the walls of the container that the gas is held in

Question 21

how to increase gas pressure

Answer 21

• increase the number of collisions per second
• increase the energy of each collision
• increase the temperature of the gas

Question 22

what happens to gas pressures at high temperatures

Answer 22

• at high temperatures, particles have higher kinetic energy
• meaning there are more collisions per second
• these are higher energy collisions

Question 23

what do particle collisions cause

Answer 23

a force which acts at right angles to the walls of the gas container
- this force, acting over the area, causes the gas pressure

Question 24

why does pressure decrease if volume increases and temperature is kept constant

Answer 24

• because we have now increased the spacing between the particles
• so now the particles can travel much further before colliding with the walls of the container and each other
• this reduces the number of collisions per second between the walls of the container and particles, reducing the pressure

Question 25

whats the relationship between pressure and volume

Answer 25

they are inversely proportional, as one increases, the other decreases