3. Particle model of matter (density of solids, liquids and gases and required practical 5: density)

Question 1

What is density?

Answer 1

How compact the particles are in a substance

Question 2

What is the equation for density?

Answer 2

Density = mass / volume

Question 3

What is density equal to?

Answer 3

Mass per unit volume

Question 4

Why do gases have a low density?

Answer 4

Because the mass of each particle is low as well as the particles having a large amount of space between them

Question 5

Why do liquids have a higher density than gases?

Answer 5

Because the mass of each particle is greater as well as the particles being arranged more compactly

Question 6

Why do solids have a high density?

Answer 6

Because it is the most compactly arranged

Question 7

What is the displacement method for irregular objects using a measuring cylinder?

Answer 7

1. First weigh the mass of your object using a weighing scale
2. Fill the measuring cylinder with water and record the initial volume
3. Tie a string around the object (as light and thin as possible)
4. And lower the object into the measuring cylinder using the string until it is full submerged
5. Then record the final volume of water
6. Then to calculate the volume of an object, take away the initial volume of water away from the final volume
7. Use the equation D = M/V to find out the density of the object

Question 8

What is the displacement method for irregular objects in a eureka can?

Answer 8

1. Find the mass of the object using a balance
2. Fill the eureka can up to the nozzle (catch any excess liquid using a beaker)
3. Lower the object into the eureka can until fully submerged
4. Catch any liquid with a measuring cylinder
5. The volume in the measuring cylinder is equal to the volume of the object
6. Use the equation D = M/V to work out the density of the object

Question 9

What will every object displace in water?

Answer 9

Their own volume

Question 10

How do you measure the density of liquids?

Answer 10

1. Measure the mass of an empty measuring cylinder using a balance
2. Then pour the liquid in and record the new mass
3. Take the initial mass away from the final mass to get the mass of the liquid
4. Measure the volume with the measuring cylinder
5. Use the equation D = M/V to work out the density of the liquid by plugging in the values you have obtained

Question 11

How do you measure the volume of cuboids/cubes?

Answer 11

Length x Width x Height

Question 12

How do you work out the volume of a cylinder?

Answer 12

Question 13

How do you work out the volume of a sphere?

Answer 13

Question 14

How are the particles in solids?

Answer 14

• they are packed closely together (regular structure)
• they are held together by very strong forces
• they vibrate about in fixed positions
• it can be difficult to change the shape

Question 15

How are the particles in liquids?

Answer 15

• packed closely: difficult to compress
• the bonds are weaker then they are in a solid
• particles can move around one another
• the particles can flow

Question 16

How are the particles in gases?

Answer 16

• they are separated by relatively large distances
• there are very weak forces between the particles
• the particles move randomly
• they can expand to fill any volume