Heating and cooling curves

Chemistry

In the Separating Substances unit, pupils will build on their knowledge of states of matter to learn about different techniques for separating mixtures.

In the Solid, Liquid and Gas States and Changes of State unit, pupils learned about the properties of different states of matter and how particles move during changes of state.

States of matter

AB: temperature of pure solid substance increases as energy is transferred to it

AB: particles remain in fixed position but vibrations increase

BC: temperature does not change but particles start to move past each other

BC: temperature does not change but particles spread apart from each other

DE: temperature does not change but particles spread apart from each other

Consider a heating curve (see image). The following statements are about some of the sections (e.g. ‘CD’ means the sloping part from C to D). Which of the statements are correct?

condensing point; liquid state; freezing point

condensing point; liquid state; solid state

The image shows three cooling curves. What do the ringed sections represent, in order from left to right?

Temperature of the solid substance increases until it reaches its melting point.

Melting point: transferred energy is used to overcome forces of attraction.

At the melting point, the temperature stays the same.

Once all the substance is in the liquid state, the temperature rises again.

Boiling point: transferred energy is used to overcome forces of attraction.

At the boiling point, the temperature stays the same. 

Once all the substance is in the gas state, the temperature rises again.

Sort the following stages of a heating curve into the correct order, starting from a statement about the solid substance:

In a heating curve experiment, the dependent variable is temperature, and the independent variable is {{}}.

Which of the following pieces of equipment would you use to measure the dependent variable in the heating curve experiment?

The image shows a curve for oxygen. This is a {{}}, although it starts at the melting point rather than with the substance in the solid state.

Sort the states of matter and the temperatures at which changes of state occur into the correct order, starting with a substance in the solid state.

Freezing and condensing are exothermic processes. Melting, evaporation and boiling are {{}} processes.

The particles in water are different to the particles in ice.

The arrangement of the particles changes as the ice melts.

On average, the particles move faster as the temperature increases.

A block of pure ice is heated in a beaker until it has all melted. Which of the following statements are correct?

change from a solid state to a liquid state

change from a liquid state to a gas state

change from a liquid state to a solid state

change from a gas state to a liquid state

Match the following keywords to their definition.

 the change of state can happen over a range of temperatures

the change of state happens at an exact temperature

Which of the following statements describe what happens when a pure substance boils and changes from the liquid state to the gas state?

the change of state can happen over a range of temperatures

Which of the following statements describes what happens when a pure substance freezes and changes from the liquid state to the solid state?

This lesson will soon be taken down.

Heating and cooling curves

Lesson outcome