Chapter 6 Molecules And Matter

Question 1

What is density

Answer 1

Density is the mass per unit volume

Question 2

Order of density of water,iron,wood highest to lowest

Answer 2

Iron
Water
Wood

Question 3

Density calculation and units

Answer 3

P=m/v
Density(g/cm^3 or kg/m^3) = mass(g or kg)/ volume (cm^3 or m^3)

Question 4

3 tools to measure length

Answer 4

Metre ruler
Standard ruler
Vernier callipers

Question 5

Describe solids flow,shape,volume,density

Answer 5

Can’t flow
Fixed shape
Fixed volume
Highest density of the states

Question 6

Describe liquids flow,shape,volume,density

Answer 6

Can flow
No fixed shape (fits container)
Fixed folume
Less dense than solid but more dense than gas

Question 7

Describe gases’ flow,shape,volume,density

Answer 7

Can flow
No fixed shape(fills container)
No fixed volume
Lowest density of the states

Question 8

What are changes of state

Answer 8

They are Physical changes between states with no new substances produced.

Question 9

What is the conservation of mass

Answer 9

When a substance changes states, the number of particles in the substance stay the same. So the mass of the substance after the change of state is the same as the mass of the substance before the change of state

Question 10

What is the kinetic theory of matter

Answer 10

matter is composed of a large number of small particles (individual atoms or molecules) that are in constant motion.

Question 11

What happens if you salt to water

Answer 11

Increases the boiling point

Question 12

What happens if you put salt in ice

Answer 12

Lowers the freezinf point so then on a road it won’t get icy until much colder

Question 13

What may change the melting and boiling point in substance

Answer 13

If there is any impurities in the substance

Question 14

Why dosen’t the temprature increase during change of state

Answer 14

As the energy is focsued on breaking the bonds instead of raising temp(changing to kinetic energy and moving round)

Question 15

What is the internal energy

Answer 15

The particles in a substance have energy, this is called ‘internal energy’ - relating to the particles motion and posistion. It’s the total kinetic(motion) and potential(posistion) energy of all the particles in a system

Question 16

Specific heat capacity calculation

Answer 16

Specific heat capacity = number of joules of heat / number of kg x number of °C of temprature change

C=E/m X change in ø

Question 17

What is latent heat

Answer 17

The energy transfered when a substance changes it state

Question 18

What is specific latent heat

Answer 18

It is the amount of energy needed to change the state of 1Kg of a substance (j/kg)

Question 19

What is the specifc latent heat of fusion and calculation

Answer 19

The amount of energy needed to change the state of 1kg of a solid to a liquid
E= m x Lf
Energy(j)= mass(kg) x latent heat of fusion(j/kg)

Question 20

What is the specific latent heat of vaporisation and caldulation

Answer 20

The amount of energy needed to change the state of 1kg of a substance from a liquid to a gas
E=M x Lf
Energy(j)= mass(kg) x latent heat of fusion(j/kg)

Question 21

How does a gas exert pressure on a surface

Answer 21

A gas exerts pressure on a surface by it randomly moving and collides with a surface with force meaning it creates pressure

Question 22

Describe how the pressure of a gas in a sealed container is affected by changing the temperature of the gas?

Answer 22

As it’s a higher temprature the particles start to move around more with higher kinetic energy meaning they vibrate more. This means that the particles collide more with a surface with stronger force and more often. So as pressure = force / surface area the force increases meaning the pressure increases

Question 23

What is gass pressure

Answer 23

Gas pressure is caused by the random collisions of particles in any surface that the gas comes into contact with

Question 24

What is brownian motion

Answer 24

The random, uncontrolled unpredictable movement of particles in a fluid (liquid or gas) as they constantly collide with other molecules

Question 25

Smoke cell example - explain how it occurs

Answer 25

1.)=a small glass cell is filled with smoke
2.)=light is shone through the cell
3.)=the smoke is viewed through a microscope
4.)=you see the smoke particles constantly moving and changing direction. The path taken by one smoke particle will look something like this

Question 26

Steps of finding density of regular solid (required practical)

Answer 26

1. Use a ruler to measure the dimensions of the object.
2. Calculate the volume (LxHxW).
3. Measure the mass of the object.
4. Calculate the density.
5. Repeat for all the objects.
6. Identify the objects using the table to the right.

Question 27

Steps to find density of irregular solid (required practical)

Answer 27

1. Place the object on a digital balance and note down its mass
2. Fill the eureka can with water up to a point just below the spout
3. Place an empty measuring cylinder below its spout
4. Carefully lower the object into the eureka can
5. Measure the volume of the displaced water in themeasuring cylinder
6. Repeat these measurements and take an average
7. The volume of the water displaced is equal to the volume of the object
8. Once the mass and volume of the shape are known, the density can be calculated using

Question 28

How to find density of liquid(required practical)

Answer 28

1. Measure the mass of the empty measuring cylinder.
2. Pour 50cm3 of the liquid into the measuring cylinder and re-weigh.
3. Calculate the mass of the liquid on its own.
4. Calculate the density of the liquid. (Remember ml and cm’ are the same!)
5. Repeat for the other solution.

Question 29

Definitins of the variables

Answer 29

Independent variable - the variable that is being changed during the experiment
Dependent variable - the variable being tested or measured during the experiment
Control variable - a variable that is kept the same during a scientific experiment

Question 30

All scientific erros and definitions and examples

Answer 30

Systametic error - are due to problems with the equipment you used. For example, the balances you used may have been out by 0.1 g for every measurement.

Random error - are due to things you have no control over, such as a change in room temperature whilst you were collecting the results. Repeating your measurements and finding a mean will reduce the effect of random errors