P1.2 Changes Of State

Question 1

What is density?

Answer 1

Density is the property of a material which is how much mass there is per unit of volume

Question 2

What is the formula for density?

Answer 2

Density(kg/m3) = mass(kg)/volume(cm3)

Question 3

What does density determine?

Answer 3

Whether an object floats or sinks. If it has a lower density than water it will float

Question 4

Why is a solid denser than a liquid?

Answer 4

A so,I’d has more particles in an area than a gas or a liquid. The mass of 1cm3 of a solid is also greater so it’s density is greater

Question 5

What does the law of conservation of mass state?

Answer 5

The mass of a system does not change unless you add or remove material. Particles do not disappear or appear

Question 6

How do you measure the volume of an irregular solid?

Answer 6

Fill an eureka can to just under the spout by slightly over filling it and letting it drain out.

Place a measuring cylinder under the spout

Gently lower the object into the eureka can

Measure the volume of liquid displaced

Repeat for reliability

Question 7

How do you measure the volume of a regular solid accurately?

Answer 7

Use a vernier calliper to measure the side lengths.

Then use an electronic mass balance

Question 8

What is temperature?

Answer 8

How hot or cold something is. Or the average kinetic energy of the particles in a substance of material

Question 9

What is absolute 0?

Answer 9

-273 Celsius

Question 10

What is the difference between energy and temperature?

Answer 10

Energy depends on the arrangement of particles and how fast they vibrate. Temperature is the average kinetic energy of each particle. This means that a swimming pool possessed more energy because it has more particles than a cup of tea but it’s temperature is lower

Question 11

What happens when a substance is heated?

Answer 11

The energy stored changes so temperature increases
A chemical reaction occurs eg combustion
A physical change occurs such as state change

Question 12

What 3 things do the amount by which temperature changes depend on?

Answer 12

The amount of energy/ temperature change

Mass of the material

The specific heat capacity of the material/ the material it is made from

Question 13

What is specific heat capacity?

Answer 13

The energy needed to raise the temperature of 1kg of a substance by 1K/C.

It is a measure of the resistance of a material to heat change

Question 14

What does heating do?

Answer 14

Increase the internal energy of particles, eg vibration or motion

Question 15

Formula for specific heat capacity

Answer 15

Delta E(J) = Mass(kg) x Specific heat capacity(J/KgC) x Delta T(C)

Question 16

Why is waters high specific heat capacity useful?

Answer 16

It can be used for central heating because it is less resistant to temperature change(decrease). Oceans will also not freeze because of this

Question 17

What happens at the Fakt section on a graph of temperature of water being heated?

Answer 17

The energy is being transferred to break the intermolecular bonds so the temperature does not increase. Internal energy increases while temperature doesn’t

Question 18

Describe the particle model of a solid?

Answer 18

Particles are in a regular and fixed position held together by very strong intermolecular forces. They do not have much energy so they vibrate when they gain energy

Question 19

Describe the particle model in a liquid

Answer 19

The particles are close together but can move around each other in an irregular arrangement. The forces of attraction are strong. The particles move in random directions at low speeds and can flow

Question 20

Describe the particle model of a gas

Answer 20

Particles are in a random arrangement with very weak intermolecular forces between them. They have more energy in their kinetic energy stores so they move in random directions at high speeds

Question 21

What happens when enough energy is provided to a solid or a liquid?

Answer 21

Solid - particles vibrate faster until the forces are overcome and the particles start to move around each other

Liquid - the particles move faster because they have more energy in their kinetic stores. Eventually the forces are overcome

Question 22

What is specific latent heat of fusion?

Answer 22

The energy transferred to cause 1 kg of a solid to turn to liquid

Question 23

What is specific latent heat of vaporisation?

Answer 23

The energy transferred to cause 1kg of a liquid to turn to gas

Question 24

What is the difference between specific latent heat and specific heat capacity?

Answer 24

Latent heat is about changing state while capacity is about temperature

Question 25

Formula for specific latent heat

Answer 25

Energy for state change(j) = mass(kg) x specific latent heat(J/kg)

Question 26

What is it specific?

Answer 26

Each material has a different latent heat and heat capacity