P1.2 Changes Of State Flashcards

1
Q

Specific Heat Capacity
Hint: equation for energy supplied

A

E = m x c x Δϴ
Energy supplied(J) = mass (kg) x SHC(J/kg oC or K) x temperature change(°C or K)
Temperature change = final - initial

Amount of energy needed to raise the temperature of 1kg of a material by 1K, or 1°C
Type of material
Mass of the material
Temperature rise

Also tells how resistant a material is to temperature change

Oil is added to the thermometer slot in the heater of an experiment setup as oil has lower SHC than air, heats up quicker.

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2
Q

Density

A

How much mass there is in a certain volume
Equation triangle:

. / M \
/D | V\

Density (kg/m ³) = mass(kg) / volume (m³)
Density of liquids is 1000x greater than gases

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3
Q

Why solids are denser than liquids and gases

A

More particles in 1cm³ in a solid than 1cm³ of the age substance in the gas state
Mass of solid is greater so its density is also greater
Density of liquids is 1000x greater than density of gases

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4
Q

Temperature

A

How hot or old something is
Measured with thermometer or temperature sensor
Measured in ° C or kelvin (K)
Difference in temperature of 1 ° Celsius = difference in 1K
Melting or boiling point of a substance would be few cm higher, 5cm higher when reading from a graph

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5
Q

Difference between temperature and energy

A

Energy measured in joules (J)
Depends on arrangement of particles and how fast they are moving or vibrating

Temperature tells about average kinetic energy of the particles

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6
Q

What stores more energy: Both are 30 ° Celsius:
Cup of water
Swimming pool

A

Swimming pool - more particles with the same kinetic energy so larger energy store

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7
Q

What happens when you heat things up

A

Changes energy stored within the system to increase temperature (water heating up)
Change of state (ice melting)
Cause chemical reactions to occur (wood burning in a bonfire)
Particles in solids vibrate faster

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8
Q

Why water is used in a central heating system

A

Resistant to temperature change

(Also means that oceans are less likely to freeze)

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9
Q

Why saucepans are made of materials with low SHC

A

Need to heat up quickly

Considerations when choosing metal to make a saucepan:
Gold and platinum have very low SHC but very expensive
Some metals are poisonous

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10
Q

What happens when sea evaporates to form water vapour

A

Energy is transferred from the thermal store of the surroundings to water
Opposite when water vapour condenses

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11
Q

Why there is no temperature rise when you melt or boil a substance

A

Internal energy is increasing even though the temperature is not
Energy transferred is breaking attractive forces between molecules of the substance

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12
Q

Specific latent heat of fusion (melting)
Specific latent heat of vaporisation

A

Energy transferred when 1kg of substance changes from solid state to liquid state or liquid state to solid state

SLC of vaporisation = energy transferred when 1kg of a substance changes from liquid to gas state

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13
Q

Specific latent heat equation

A

Thermal energy for a change in state(J) = mass(kg) x SLH(J/kg)

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14
Q

Specific latent heat vs specific heat capacity

A

Both involve energy changes for 1kg of a substance

Latent heat is about change of state but heat capacity is about change of temperature

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