New
New
Year 8

Cooling curve: practical

I can conduct an investigation to create and analyse cooling curves and identify where state changes are happening on temperature vs time graphs.

New
New
Year 8

Cooling curve: practical

I can conduct an investigation to create and analyse cooling curves and identify where state changes are happening on temperature vs time graphs.

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Lesson details

Key learning points

  1. State changes are visible as plateaus on cooling curves.
  2. As it cools, a substance transfers energy into the surroundings by heating and it may condense or freeze.
  3. Energy is released to the surroundings as a substance cools and this is observed as a decrease in substance temperature.
  4. Graphs provide a visual representation of data for easier analysis and help identify trends/patterns.

Common misconception

All substances freeze when really cold, like water.

Show state changes using particle diagrams / kinetic energy model. Challenge pupils to identify state given real world temperature data.

Keywords

  • Plateau - A plateau is a section of a graph that does not change value (stays at the same level for a period of time).

  • Melting point - The melting point of a substance is the temperature at which it changes from solid state to a liquid state.

  • Freezing - Freezing is the process of a substance changing from a liquid state to a solid state.

  • Temperature - Measured using a thermometer (commonly in °C). Temperature is an indirect measure of the energy of the particles in a substance.

This lesson is designed to investigate tert-butyl alcohol (low m.p. of 26℃) but could be adapted to use other substances like salol, stearic acid etc. Check CLEAPSS for guidance. As a result, the lesson's tasks will need to be updated to match.
Teacher tip

Content guidance

  • Equipment requiring safe usage.

Supervision

Adult supervision recommended.

Licence

This content is © Oak National Academy Limited (2024), licensed on Open Government Licence version 3.0 except where otherwise stated. See Oak's terms & conditions (Collection 2).

Video

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6 Questions

Q1.
Which of the following is the most appropriate way to show the change in temperature over time?
Bar chart
Pie chart
Correct answer: Line graph
Q2.
The term used to describe the energy transfer from an object to its surroundings as it cools is...
Correct Answer: exothermic
Q3.
True or false? In the gas state, particles have enough energy to move freely and are not held in fixed positions.
Correct Answer: true, True, true.
Q4.
What happens to the particles of a substance when it is heated and reaches its boiling point?
They stop moving.
They move closer together.
Correct answer: They move further apart and move more quickly.
They change colour.
Q5.
The temperature at which a substance changes from solid to liquid is known as its...
Correct Answer: melting point, melting-point, meltingpoint
Q6.
Match the state of matter to the description about forces of attraction.
Correct Answer:substances in the solid state,particles have the strongest forces of attraction

particles have the strongest forces of attraction

Correct Answer:substances in the liquid state,particles have some (weakened) forces of attraction

particles have some (weakened) forces of attraction

Correct Answer:substances in the gas state,particles have fully overcome forces of attraction

particles have fully overcome forces of attraction

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6 Questions

Q1.
On a heating curve, what does a plateau indicate?
An image in a quiz
A temperature increase.
Correct answer: A constant temperature during a state change.
An error in measurement.
The substance is not changing state.
The substance is no longer being heated.
Q2.
The point on a cooling curve where a liquid starts to solidify is called the point.
Correct Answer: freezing
Q3.
How does energy transfer during the cooling of a substance?
Energy is absorbed from the surroundings.
Correct answer: Energy is released into the surroundings.
Energy remains constant in the substance.
Q4.
Which state changes are shown in this heating curve?
An image in a quiz
melting only
Correct answer: melting and boiling
boiling only
freezing only
freezing and condensing
Q5.
At what temperature (℃) does this substance begin to melt? (give only the number, not the unit)
An image in a quiz
Correct Answer: 20, twenty, 20℃, 20°C, twenty degrees
Q6.
Why does a substance's temperature not change during a phase transition, despite continued heating?
Because the substance is losing energy.
Correct answer: Because the energy is used to overcome forces of attraction.
Because the heating process stops temporarily.
Because the temperature measurement is incorrect (an error in recording).
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