Section 5- Soilds, Liguids and Gases P2

Question 1

What are the differences between particles of the same state?

Answer 1

the arrangement and energy of the particles are different

Question 2

What theory can explain the three states of matter?

Answer 2

Kinetic theory

Question 3

What are the properties of particles in a solid?

Answer 3

• strong forces of attraction between the particles
• particles close together in a fixed, regular arrangement
• particles don’t have much energy so only vibrate about their fixed positions

Question 4

What are the properties of particles in a liquid?

Answer 4

• weaker forces of attraction between particles
• particles are close together, but can move past each other, form irregular arrangements
• more energy than solid particles
• move in random directions at low speeds

Question 5

What are the properties of particles in a gas?

Answer 5

• almost no forces of attraction between them
• particles have more energy than liquids and solids
• free to move particles, travel in random directions at high speeds

Question 6

What is the thermal energy store of a substance?

Answer 6

The energy in a substance’s thermal energy store is held by its particles in their kinetic energy stores.

Question 7

When you heat a liquid what happens to the particles?

Answer 7

• the extra energy is transferred to the particles’ kinetic energy stores, making them move faster
• eventually, when enough of the particles have enough energy to overcome their attraction to each other
• bubbles of gas form in the liquid(this is boiling)

Question 8

When a substance is melting or boiling what happens to the energy you input?

Answer 8

-the energy is used for breaking intermolecular bonds rather than raising the temperature, so a substance stays at a constant temperature

Question 9

When a substance is condensing or freezing what happens to the substance when it is at the point of changing state?

Answer 9

• bonds are forming between particles, which releases energy

- the temperature doesn’t go down until all of the substance has changed state

Question 10

What is evaporation?

Answer 10

Evaporation is when particles escape from a liquid and become gas particles

Question 11

Why is evaporation a special example of changing states?

Answer 11

Particles can evaporate from a liquid at temperatures that are much lower than the liquids boiling point.

Question 12

What are the conditions by which evaporation can occur?

Answer 12

• if the particles are travelling in the right direction to escape the liquid
• if the particles are travelling fast enough(have enough kinetic stores), overcome the attractive forces of the other particles in the liquid

Question 13

What is the effect to the energy of the particles when particles leave the liquid and evaporate?

Answer 13

• the fastest particles with the most energy are most likely to evaporate
• when they evaporate the average speed and temperature of the remaining particles decrease
• the liquid cools as a result

Question 14

How can the cooling effect of evaporation be useful?

Answer 14

You sweat when you exercise or get hot

-as the water on your skin evaporates, you cool down`

Question 15

Describe a practical for how to obtain a temperature-time graph for water?

Answer 15

• fill a beaker with crushed ice, place a thermometer in and record the temperature
• use a Bunsen burner to heat the ice
• every 20secs record the temperature and the current state of the ice, continue until the water boils
• plot a graph of temperature against time

Question 16

How should a graph look for the heating of ice to steam?

Answer 16

• proportionally increasing to 0°C where it levels
• then increases again to 100°C where it levels
• then increases

Question 17

What is another name for the thermal energy store of a substance?

Answer 17

the internal energy of a substance

Question 18

Is there a difference in the amount of energy required to increase the temperature of different materials.

Answer 18

Yes

• need 4200J of energy per kg of water to raise 1°C
• need 139J of energy per kg of mercury to raise 1°C

Question 19

What is the equation for working out the specific heat capacity?

Answer 19

𐤃Q = m x c x 𐤃T
𐤃Q (change in thermal energy J)
m (mass kg)
c (specific heat capacity J/kg°C)
𐤃T (change in temperature °C)

Question 20

Describe a practical for how to find the specific heat capacity of water?

Answer 20

• use a mass balance to find the mass of the water (taring the container first) (use an insulated container)
• record the temp of the liquid
• heat the liquid and use a joulemeter to find out how many joules are given off for the temperature to increase by 10°C
• use the specific heat capacity equation
• repeat at least 3 times

Question 21

How can you measure the specific heat capacity of a solid?

Answer 21

• the block must have two holes, for the heater and thermometer
• wrap the solid in an insulated layer
• once you’ve heated by a set amount and recorded the joules on the joulemeter
• wait until the temperature stops increasing before recording the highest temperature