P1.2

Question 1

What is temperature

Answer 1

Temperature is how hot or cold something is.

Question 2

Temperature units

Answer 2

C (degrees Celsius) and K (Kelvin) are both units of temperature

-273 C = 0 K
0C = 273K

Question 3

Difference between energy and temperature

Answer 3

Energy in a thermal store in Joules (J). It depends on the arrangement of the particles and how fast they are moving or vibrating. Temperature tells you about the average kinetic energy of the particles

Question 4

What happens when you heat things up?

Answer 4

• There’s a change in the energy stored within the system to increase temperature (e.g ready for your hot shower)
  
  • Produce a change of state (such as ice melting)
  • Make chemical reactions happen (such as wood burning)

Question 5

Physical change

Answer 5

Dissolving is a physical change, no new substances are made and they are easy to reverse. This is because the particles are simply rearranged

Question 6

Chemical reaction

Answer 6

Chemical reactions such as burning, involve joining atoms together in different ways. You cannot easily reverse a chemical change.

Question 7

Which object has the least energy in a thermal store: a cup of hot water; a saucepan of hot water; a cup of cold water

Answer 7

a cup of cold water

Question 8

Why is cooking an egg is not reversible, but melting butter is?

Answer 8

Cooking an egg is not reversible since it is a chemical change where a new substance is made whereas melting butter is because it is a physical change and only a change of state is occurring

Question 9

What is specific heat capacity?

Answer 9

The amount of energy needed to raise the temperature of 1kg of a material by 1K (kelvin). The unit of specific heat capacity is (J/kg K)

Question 10

Where does specific heat capacity make a difference?

Answer 10

Specific heat capacity tells you how resistant a material is to change in temperature

Question 11

Water

Answer 11

Water is especially resistant to temp change. This makes it a good material to use in a central heating system. It also means that oceans are less likely to freeze

Question 12

Saucepans

Answer 12

Saucepans are made of materials with low specific heat capacities because they need to heat up quickly.

Question 13

What happens when substances change their state?

Answer 13

You need to heat or cool a substance to produce a change of state. Water in lakes or the sea evaporates to form water vapour. The energy is transferred from the thermal store of the surroundings to the water. When water vapour condenses energy is transferred from the water to the surroundings. This where much of the energy fro tropical storms comes from.

Question 14

What is latent heat?

Answer 14

The specific latent heat of fusion is the energy is transferred when 1kg of a substance changes from the solid state to the liquid state , or from the liquid state to the solid state. The specific latent heat of vaporisation is the energy transferred when 1kg of a substance changes from liquid to gas

Question 15

How do you calculate with specific latent heat?

Answer 15

You need to apply this equation to calculate with specific latent heat:
Thermal energy for a change in state (J) = mass (kg) * specific latent heat (J/kg)

Question 16

How is specific latent heat different from specific heat capacity?

Answer 16

Latent heat is about change while heat capacity is about change of temperature

Question 17

Describe the changes of state in taking ice from a freezer, putting it in a saucepan, and heating until the saucepan is empty?

Answer 17

When you take the ice out of the freezer and put it in a saucepan, it will start to change to a liquid state. When you heat the liquid, it will start to evaporate and therefore will be nothing in the saucepan.