Changes of state (P1.2) | OCR GCSE Combined Science A (Gateway Science) — Physics — Foundation (J250)

P1.2 Changes of state

Summary A clear understanding of the foundations of the physical world forms a solid basis for further study of physics. Understanding of the relationship between the states of matter helps to explain different types of everyday physical changes that we see around us. Underlying knowledge and understanding Learners should be familiar with the structure of matter and the similarities and differences between solids, liquids and gases. They should have an idea of the particle model and be able to use it to model changes in particle behaviour during changes of state. Learners should be aware of the effect of temperature in the motion and spacing of particles and an understanding that energy can be stored internally by materials.

Common misconceptions Learners commonly carry misconceptions about matter: assuming atoms are always synonymous with particles. Learners also struggle to explain what is between the particles, instinctively ‘filling’ the gaps with ‘air’ or ‘vapour’. They often struggle to visualise the 3D arrangement of particles in all states of matter. Learners can find it challenging to understand how kinetic theory applies to heating materials and how to use the term temperature correctly, regularly confusing the terms temperature and heat.

Reference	Mathematical learning outcomes	Maths skills
$PM1.2i$

Learning outcomes	To include	Maths	Working scientifically	Practical suggestions
$P1.2a describe how mass is conserved when substances melt, freeze, evaporate, condense or sublimate$			$WS1.3a, WS1.3e, WS1.4a, WS2a, WS2c$	$Use of a data logger to record change in state and mass at different temperatures. (PAG P5) Demonstration of distillation to show that mass is conserved during evaporation and condensation. (PAG P5)$
$P1.2b describe that physical changes differ from chemical changes because the material recovers its original properties if the change is reversed$
$P1.2c describe how heating a system will change the energy stored within the system and raise its temperature or produce changes of state$			$WS1.3a, WS1.3e, WS1.4a, WS2a, WS2b, WS2c$	$Observation of the crystallisation of salol in water under a microscope. Use of thermometer with a range of 10 -110 °C, to record the temperature changes of ice as it is heated. (PAG P1)$
$P1.2d define the term specific heat capacity and distinguish between it and the term specific latent heat$	$specific latent heat of fusion and specific latent heat of vaporisation$		$WS1.2e, WS1.3b, WS1.3c, WS1.3h, WS1.4a, WS1.4f, WS2a, WS2b$	$Investigation of the specific heat capacity of different metals or water using electrical heaters and a joulemeter. (PAG P5)$
$P1.2e apply the relationship between change in internal energy of a material and its mass, specific heat capacity and temperature change to calculate the energy change involved$		$M1a, M3c, M3d$
$P1.2f apply the relationship between specific latent heat and mass to calculate the energy change involved in a change of state$		$M1a, M3c, M3d$	$WS1.2e, WS1.3b, WS1.3c, WS1.3h, WS1.4a, WS1.4f, WS2a, WS2b$	$Measurement of the specific latent heat of vaporisation of water. (PAG P5) Measurement of the specific latent heat of stearic acid. (PAG P5)$
$P1.2g explain how the motion of the molecules in a gas is related both to its temperature and its pressure$	$application to closed systems only$	$M1c, M4a, M5b$	$WS1.1b, WS1.2a, WS1.2e, WS1.3e, WS1.4a, WS2a$	$Demonstration of the difference in pressure in an inflated balloon that has been heated and frozen. (PAG P1) Building manometers and using them to show pressure changes in heated/ cooled volumes of gas. (PAG P1)$
$P1.2h explain the relationship between the temperature of a gas and its pressure at constant volume (qualitative only)$		$M1c, M5b$	$WS1.1b, WS1.2a, WS1.2e, WS1.3e, WS1.4a, WS2a$	$Demonstration of the exploding can experiment. Building of Alka-Seltzer rockets with film canisters.$

Learning outcomes

To include

Maths

Working scientifically

Practical suggestions

P1.2a describe how mass is conserved when substances melt, freeze, evaporate, condense or sublimate

WS1.3a, WS1.3e, WS1.4a, WS2a, WS2c

Use of a data logger to record change in state and mass at different temperatures. (PAG P5) Demonstration of distillation to show that mass is conserved during evaporation and condensation. (PAG P5)

P1.2b describe that physical changes differ from chemical changes because the material recovers its original properties if the change is reversed

P1.2c describe how heating a system will change the energy stored within the system and raise its temperature or produce changes of state

WS1.3a, WS1.3e, WS1.4a, WS2a, WS2b, WS2c

Observation of the crystallisation of salol in water under a microscope. Use of thermometer with a range of 10 -110 °C, to record the temperature changes of ice as it is heated. (PAG P1)

P1.2d define the term specific heat capacity and distinguish between it and the term specific latent heat

specific latent heat of fusion and specific latent heat of vaporisation

WS1.2e, WS1.3b, WS1.3c, WS1.3h, WS1.4a, WS1.4f, WS2a, WS2b

Investigation of the specific heat capacity of different metals or water using electrical heaters and a joulemeter. (PAG P5)

P1.2e apply the relationship between change in internal energy of a material and its mass, specific heat capacity and temperature change to calculate the energy change involved

M1a, M3c, M3d

P1.2f apply the relationship between specific latent heat and mass to calculate the energy change involved in a change of state

M1a, M3c, M3d

WS1.2e, WS1.3b, WS1.3c, WS1.3h, WS1.4a, WS1.4f, WS2a, WS2b

Measurement of the specific latent heat of vaporisation of water. (PAG P5) Measurement of the specific latent heat of stearic acid. (PAG P5)

P1.2g explain how the motion of the molecules in a gas is related both to its temperature and its pressure

application to closed systems only

M1c, M4a, M5b

WS1.1b, WS1.2a, WS1.2e, WS1.3e, WS1.4a, WS2a

Demonstration of the difference in pressure in an inflated balloon that has been heated and frozen. (PAG P1) Building manometers and using them to show pressure changes in heated/ cooled volumes of gas. (PAG P1)

P1.2h explain the relationship between the temperature of a gas and its pressure at constant volume (qualitative only)

M1c, M5b

WS1.1b, WS1.2a, WS1.2e, WS1.3e, WS1.4a, WS2a

Demonstration of the exploding can experiment. Building of Alka-Seltzer rockets with film canisters.

Changes of state

Next Steps

Learning Objectives