New
New
Year 10
OCR
Foundation

Energy changes: neutralisation practical

I can perform a practical to measure the temperature change in a neutralisation reaction, record results, analyse data, and conclude if the reaction is exothermic or endothermic.

New
New
Year 10
OCR
Foundation

Energy changes: neutralisation practical

I can perform a practical to measure the temperature change in a neutralisation reaction, record results, analyse data, and conclude if the reaction is exothermic or endothermic.

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Lesson details

Key learning points

  1. Neutralisation reactions involve an acid reacting with a base to form salt and water.
  2. Exothermic reactions release energy to the surroundings, often through heating.
  3. Methods must be detailed and replicable for reliable data collection.
  4. The initial and final temperatures of the reaction mixture need to be recorded to calculate energy change.
  5. Line graphs can illustrate relationships between continuous variables in experiments.

Keywords

  • Neutralisation - Neutralisation is when a chemical reaction takes place between an acid and base to produce a neutral solution of a salt and water.

  • Exothermic - An exothermic reaction is a type of reaction in which energy is transferred from the reactants to the surroundings e.g. combustion.

  • Method - A method describes how an experiment is carried out; it is a step-by-step procedure.

  • Line graph - A line graph involves two continuous variables being plotted to show if a relationship exists between them. Any trends in the data are shown with the addition of a line of best fit.

  • Conclusion - A conclusion sums up what has been found out during an investigation. It always refers to both the independent and dependent variables.

Common misconception

Pupils can assume that any decrease in temperature occurring when excess reactant is added to an exothermic reaction is because the reaction has become endothermic.

Explain that once the limiting reactant has been used up the exothermic reaction is complete. The addition of excess reactant will only act to cool down the reaction mixture.

Use analogies such as what would happen to a hot cup of tea if you added cold water.
Teacher tip

Equipment

class set of polystyrene cups and lids, thermometers, measuring cylinders, stirring rods, hydrochloric acid and sodium hydroxide solutions

Content guidance

  • Risk assessment required - equipment

Supervision

Adult supervision required

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).

Lesson video

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6 Questions

Q1.
What is an exothermic reaction?
A reaction that absorbs energy from the surroundings
A reaction that neither releases nor absorbs energy
Correct answer: A reaction that releases energy to the surroundings
Q2.
What is an endothermic reaction?
Correct answer: A reaction that absorbs energy from the surroundings
A reaction that neither releases nor absorbs energy
A reaction that releases energy to the surroundings
Q3.
What is the pH range of acidic solutions?
0 to 14
Correct answer: 0 to 6
7 to 14
Q4.
What is the pH range of alkaline solutions?
0 to 6
7 to 14
Correct answer: 8 to 14
Q5.
What does a pH indicator do?
Correct answer: Changes colour to show if a solution is acidic or alkaline
Measures the temperature of a solution
Reacts with acids and bases to produce gas
Q6.
What is a neutralisation reaction?
A reaction between a base and a metal
Correct answer: A reaction between an acid and an alkali to form water and a salt
A reaction between two acids

6 Questions

Q1.
In the neutralisation practical, why is it important to measure the initial temperature of the hydrochloric acid?
To check the purity of the acid
Correct answer: To determine the temperature change during the reaction
To ensure the acid is at room temperature
Q2.
What is the primary reason for the temperature increase during a neutralisation reaction?
Energy is absorbed as bonds break in the acid and alkali
Energy is released as gas forms
Correct answer: Energy is released as heat when bonds form between water molecules
Q3.
What is the dependent variable in the neutralisation experiment?
The amount of salt formed
Correct answer: The temperature change of the reaction mixture
The volume of hydrochloric acid used
Q4.
Why is it important to use a polystyrene cup when conducting the neutralisation experiment?
Polystyrene changes colour to indicate the completion of the reaction
Correct answer: Polystyrene is an insulator that minimises heat loss to the surroundings
Polystyrene reacts with the acid to produce more accurate results
Q5.
How can you experimentally determine whether a neutralisation reaction is exothermic or endothermic?
Measure the pH change before and after the reaction
Correct answer: Measure the temperature change of the reaction mixture before and after
Observe the colour change of the indicator
Q6.
If 25 cm³ of hydrochloric acid reacts with 25 cm³ of sodium hydroxide, what will be the final pH of the solution?
Approximately 1, indicating a highly acidic solution
Approximately 14, indicating a highly alkaline solution
Approximately 7, indicating a neutral solution