Chemistry

Question 1

What are the 5 parts of a Bunsen burner? Describe each part.

Answer 1

1. Base - to stop it falling over, the Bunsen burner has a heavy base
2. Rubber tube - gas comes into the Bunsen burner through a rubber tube
3. Airhole - to help the gas burn, some air can enter through the air hole
4. Collar - you can change the amount of air you let in by turning the collar, this opens or closes the air hole. If you let in more air, the flame is hotter and roars.
5. Chimney - the mixture of gas and air rises up the chimney and is lit at the top.

Question 2

What is at the bottom of the flame?

Answer 2

A blue cone - this is cold, unburnt gas. The flame is hottest above the blue cone.

Question 3

Why does the Bunsen burner have a heavy base?

Answer 3

So it doesn’t fall over

Question 4

Where does the gas enter the Bunsen burner?

Answer 4

The rubber tube

Question 5

How can you make the flame hotter?

Answer 5

By turning the collar and opening the air hole. This lets more air in and the flame becomes hotter.

Question 6

Where is the flame hottest?

Answer 6

The flame is hottest above the blue cone.

Question 7

Why is it no use trying to heat something too close to the opening of the chimney?

Answer 7

At the opening of the chimney is the blue cone which is cold, unburnt gas.

Question 8

What is the definition of ‘Properties’?

Answer 8

The way a substance looks and behaves.

Question 9

What are the states of matter?

Answer 9

Solids, liquids and gases

Question 10

What is ‘Density’?

Answer 10

The mass of something compared to its volume.

Density is how much mass there is per volume of a substance (how heavy something is for its size)

Question 11

Why do solids, liquids and gases all have different properties?

Answer 11

It is because of the way the particles are arranged inside the substances.

Question 12

What is the arrangement of particles in a solid?

Answer 12

The particles are very close together in an ordered arrangement
The particles vibrate in a fixed position
The particles have very strong forces between them

Question 13

What is the arrangement of particles in liquid?

Answer 13

The particles are close together
The particles are free to move below the surface
The particles vibrate and move round each other
The particles have quite strong forces between them

Question 14

What is the arrangement of particles in a gas?

Answer 14

The particles are far apart in a random arrangement
The particles are free to move anywhere
The forces between the particles are weak

Question 15

Describe the arrangement of particles in a solid, liquid and gas

Answer 15

Solid - very close together, regular arrangement
Liquid - close together, random arrangement
Gas - far apart, random arrangement

Question 16

Describe the motion of particles in a solid, liquid and gas

Answer 16

Solid - vibrates about a fixed position
Liquid - moves around each other
Gas - moves quickly in all directions

Question 17

Describe the properties of a solid, liquid and gas

Answer 17

Solid - definite shape, definite volume, not compressible
Liquid - takes the shape of container, definite volume, not compressible
Gas - does not stay in an open container, spreads out to fill available volume, volume depends on container, compressible

Question 18

How can a substance change its state?

Answer 18

When the particles of a substance gains or loses energy, the substance may change its state

Question 19

Describe melting

Answer 19

If energy is supplied to a solid, its particles vibrate more violently
They may separate from each other and become free to move
The temperature at which a solid melts is called its melting point

Question 20

Describe evaporation

Answer 20

Heating a liquid makes its particles move around more quickly
Particles which have enough energy may overcome attractive forces
They will escape from the liquid and become a gas
This is evaporation

Question 21

Describe boiling

Answer 21

When the temperature is higher, more particles have enough energy to escape so evaporation is faster
If the temperature is high enough, a liquid will boil
The temperature at which a liquid boils is called its boiling point

Question 22

Describe diffusion

Answer 22

The particles of a gas move around very quickly in all directions
This is why gases spread out (diffuse) and mix completely with each other

Question 23

Describe dissolving

Answer 23

As liquid particles move about, they may separate the particles of an added solute from each other
This is dissolving

Question 24

(picture of a beaker, bung and funnel)

The funnel is filled with water, but the water does not run into the flask. Why is this?

Answer 24

The air is taking up all of the space so there is no room for the liquid

Question 25

(picture of a beaker, bung and funnel with water) | What would you do to get the water into the flask?

Answer 25

Remove the bung so that all the air can escape so the water has space to rush out

Question 26

(picture of 2 balloons balanced at the ends of a ruler) | Why does the ruler not stay horizontal after one balloon is popped?

Answer 26

The balloon with more air in it was heavier than the balloon that was popped It is heavier because the air in the balloon adds mass to the balloon This shows that air has mass

Question 27

The volume of a gas depends on _________ | The volume of a gas also depends on ________

Answer 27

Pressure | Temperature

Question 28

# Fill a plastic syringe with air. Put your finger over the nozzle. a) What happens when you press gently on the plunger? | b) What happens when you press harder on the plunger?

Answer 28

a) This decreases the volume of the gas which increases the pressure of the gas. You can feel a slight pressure on your finger. b) When you press harder, the volume decreases more and the gas particles will have less room to move, the pressure will increase further

Question 29

You can squash the gas by increasing the______

Answer 29

pressure

Question 30

How does temperature affect the volume of gas?

Answer 30

The higher the temperature, the larger the volume that has been taken up by the gas. The lower the temperature, the smaller the volume taken up by the gas.

Question 31

An object will _____ if it is _____ dense than water | An object will _____ if it is _____ dense than water

Answer 31

float, less dense | sink, more dense

Question 32

How do you calculate density?

Answer 32

Density = mass/volume | Density equals mass divided by volume

Question 33

What are the units used in measuring density?

Answer 33

g/cm3 (gram per cubic centimetre)

Question 34

How do you find the volume of an object?

Answer 34

height x width x length

Question 35

What is the density of water?

Answer 35

1 gm/cm3

Question 36

A wooden block has a mass of 5 g and a volume of 10 cm3, what is its density

Answer 36

0.5 g/cm3

Question 37

If a perfume is sprayed in one corner of the room, it takes a few minutes for the smell to reach the other side of the room. Why is this?

Answer 37

The particles are slowed down by collision with air particles