# 2 Gas Laws Flashcards

1
Q

How is P1 and T1 related to P2 and T2?

P1 is pressure before

T1 is temperature before

P2 is pressure after

T2 is temperature after

A
2
Q

Explain why a hot balloon expands

A

As temperature rises, the particles have more energy

Particles have more KE

Particles move faster

More collisions per unit time AND particles collide with more force

Pressure = force / area

Increased pressure on the inside of the balloon, with same pressure on the outside results in greater forces on inside compared to outside of balloon - balloon skin stretches outward

3
Q

What are the control variables for the Boyles’ Law investigation where the volume of a gas was measured as the pressure was varied?

A

Moles or mass of gas

Temperature of gas

4
Q

Use the equation below to calculate the new volume of a gas as its pressure increased from 100kPa to 200kPa.

Its initial volume was 50cm3.

A

P2V2 = P1 V1

V2 = P1V1/P2

V2 = 100kPa x 50cm3 / 200kPa

V2 = 25cm3

5
Q

Convert 373K to ºC

A

ºC = K - 273

373K = 100ºC

6
Q

How does a gas exert pressure of the inside of a balloon?

A
1. Gas particles are moving fast and freely
2. They collide with the walls of the balloon
3. They exert a force of the wall of the balloon
4. Pressure = force / area
5. Particles exerting a force on the area of the balloon creates a pressure.
7
Q

Convert 100K to ºC

A

ºC = K - 273

100K = -173ºC

8
Q

Name the independent and dependent variable for the Joly’s bulb experiment

A

Independent : temperature gas

Dependent : pressure of gas

9
Q

What happens to the pressure of a gas if the volume is halved?

Explain why this happens.

A

As volume is halved, pressure is doubled

There are the same number of particles as the volume is halved

OR double the number of particles per unit volume

Pressure = force / area

Double the number of collision per unit time per unit area.

10
Q

Name the independent and dependent variable for Boyle’s law experiment

A

Independent : pressure

Dependent : volume of gas

11
Q

What happens to the particles of a gas when they are heated?

A

The particles gain energy

KE of particles increases

Particles move faster

12
Q

Convert 100ºC to Kelvin

A

K = ºC + 273

100ºC = 373 K

13
Q

How would you represent the motion of a smoke particles in air? (Brownian motion)

A

Uses arrows of different length and directions to show continual random movement.

14
Q

What is the unit for volume of a gas?

A

cm3 or dm3

15
Q

How many Pa is a kPa?

A

1000 Pa = 1 kPa

16
Q

From the graph, how is pressure of a gas related to its volume at the same temperature and moles of gas?

A

Pressure is inversely proportional to volume at same temperature and moles of gas

17
Q

Convert -273ºC to Kelvin

A

K = ºC + 273

-273ºC = 0 K

18
Q

A pupils stated that as the temperature of a gas in degrees celsius is doubles, the kinetic energy of the gas must also double.

Is this statement true or false?

A

False

At t_emperature of a gas in kelvin doubled,_ the average kinetic energy of the particles doubles

Temperature must be in kelvins!!

19
Q

How is P1 and V1 related to P2 and V2?

P1 is pressure before

V1 is volume before

P2 is pressure after

V2 is volume is after

A
20
Q

Use the pressure-temperature equation to work out the new temperature for a gas where the pressure was decreased from 100kPa to 50kPa

Intial temperature was 40K.

A

T2/P2 = T1/P1

(write the equation with T2 first- this makes it easier to rearrange!!)

T2= T1P2/P1

T2= 40K x 50kPa / 100kPa

T2 = 20K

21
Q

How can Brownian motion be observed?

A

Random jerky movement of smoke particles in a smoke cell through a microscope

22
Q

What is the unit for pressure

A

Pascal (Pa)

kilopascal (kPa)

atmospheres (atm)

23
Q

A pupils stated that as the temperature of a gas in kelvin is doubled, the average speed of the gas must also double.

Is this statement true or false?

A

False

At t_emperature of a gas in kelvin doubles,_ the average kinetic energy of the particles doubles, NOT the average speed

24
Q

Why does an air balloon grow bigger when air is heated

A

As temperature of a gas increases, kinetic energy increases

particles move with greater speed and hit the sides of the balloon more frequently AND with more force

Pressure = force / area

Greater force on walls of balloon increases the pressure of the gas pushing the walls of the balloon outward.

25
Q

From the graph, how is pressure related to temperature in kelvin of a gas - at the same volume and mole of gas?

A

Pressure is proportional to temperature in kelvin at the same volume and moles of gas

26
Q

What is Brownian motion?

A

It is the continuous and random zig zag movement of microscopic particles in a fluid, as a result of continuous bombardment from molecules of the surrounding medium.

(pollen in water)

27
Q

Use the equation below to calculate the original pressure of a gas as its volume increased from 50cm3 to 100cm3

Its final pressure was 40kPa.

A

P<span>1</span>V<span>1</span> = P2 V2

P1 = P2V2/V1

P1 = 40kPa x 100cm3 / 50cm3

P1 = 80kPa

28
Q

Use the equation below to calculate the new pressure of a gas as its volume decreased from 100cm3 to 50cm3.

Its initial pressure was 1atm.

A

P2V2 = P1 V1

P2 = P1V1/V2

P2 = 1atm x 100cm3 / 50cm3

P2 = 2atm

29
Q

How is pressure of a gas related to its volume?

What would a graph of pressure against volume look like?

A

Pressure is inversely proportional to volume

As pressure doubles, volume halves

(For same moles of gas and temperature)

30
Q

State Boyle’s Law

A

Pressure is inversely proportional to volume- at a constant temperature.

If pressure of a gas is doubled, its volume would halve

31
Q

A pupils stated that as the temperature of a gas in kelvin is doubles, the average speed of the gas must also double.

Is this statement true or false?

A

False

At t_emperature of a gas in kelvin doubles,_ the average kinetic energy of the particles doubles, NOT the average speed

32
Q

How is temperture related to the average KE of particles

A

Temperature is proportional to the average KE of the particles

NOTE: Temperature is not proportional to the average velocity of the particles!!

33
Q

What happens to the pressure inside a tyre in the summer?

A
1. As temperature increases, energy of gas particles increases
2. In_crease in KE_ of particles means particles move more quickly
3. Particles collide with the wall more frequently AND with more force
4. Pressure = Force / area
5. More force on the same area results in more pressure.
34
Q

What are the control variables for the investigation where pressure of a gas was measured as temperature was varied?

A

Moles/mass of gas

Volume of gas

35
Q

Use the pressure-temperature equation to work out the initial pressure for a gas where the temperature was increased from 100K to 200K

Final pressure was 5 atm.

A

P1/T1 = P2/T2

(write the equation with P1 first- this makes it easier to rearrange!!)

P1= P2T1/T2

P1= 5atm x 100K / 200K

P1 = 2.5atm

36
Q

How does the pressure of a gas relate to it temperature in kelvin?

What would a graph of pressure against temperature look like?

A

Pressure is proportional to temperature in kelvin

(For same moles of gas and volume)

Straight time through the origin

37
Q

How many cm3 in a dm3?

A

1 dm3 = 1000 cm3

38
Q

What happens to the pressure inside a tyre in the winter?

A
1. As temperature decreases, energy of gas particles decreases
2. Decrease in KE of particles means particles move more slowly
3. Particles collide with the wall less frequently AND with less force
4. Pressure = Force / area
5. Less force on the same area results in less pressure.
39
Q

How is pressure related to temperature in degrees celsius?

A

Pressure is linearly related to temperature in degrees celsius.

(For same moles of gas and volume)

It is a straight line but does not go through the origin.

40
Q

Convert 0ºC to Kelvin

A

K = ºC + 273

0ºC = 273 K

41
Q

Convert 0K to ºC

A

ºC = K - 273

0K = -273ºC

42
Q

Use the pressure-temperature equation to work out the initial temperature for a gas where the pressure was decreased from 100Pa to 50Pa

final temperature 15K.

A

T1/P1 = T2/P2

(write the equation with Ti first- this makes it easier to rearrange!!)

T1= T2P1/P2

T1= 15K x 100Pa /50Pa

T1 = 30K

43
Q

Use the pressure-temperature equation to work out the new pressure for a gas where the temperature was increased from 100K to 200K

Intial pressure was 3 atm.

A

P2/T2 = P1/T1

(write the equation with P2 first- this makes it easier to rearrange!!)

P2= P1T2/T1

P2= 3 atm x 200K / 100K

P2 = 6atm

44
Q

Describe the movement of particles in a gas

A

Fast, freely and randomly