Illustrate the link between neutralising acids with alkalis and changes in ionic concentrations

Demonstrate a conductometric titration of barium hydroxide with sulfuric(VI) acid to strengthen your learners’ mental models of particles reacting in solution. This experiment is a great way to emphasise the ionic and molecular nature of one of the first ionic equations learners are likely to meet: a neutralisation reaction in which hydroxide ions react with hydrogen ions. 

Watch the Exhibition chemistry video and download the technician notes before carrying out the acid-alkali neutralisation, using this worksheet to develop your learners’ understanding of ions. 

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    A student sheet and teacher notes available as PDFs or MS Word docs.

Learning objectives

  • Identify the ions present in acidic and alkaline solutions.
  • Describe the changes in ionic concentrations in an acid–alkali neutralisation.

Teacher notes

Use the conductometric titration worksheet to help your learners practice identifying ions present in solution, writing ionic equations and describing the changes in ionic concentrations in an acid–alkali neutralisation. The teacher notes contain the answers to the questions, which can be used in class following the demonstration or as homework to consolidate your learners’ understanding. 

Questions

1. (a) What do you call the particles in a solution that conducts electricity?

(b) What are the names of these particles in the two solutions being used? Write the symbols for these particles.

2. (a) What has happened to the number of ions present in the solution when the endpoint is reached?

(b) If the precipitate is barium sulfate, which ions does this remove from the solution?

3. (a) What other ions are present at the start of the titration?

(b) What must have happened to these ions when the endpoint is reached?

4. Write an ionic equation for the reaction between the ions identified in question 3.

5. Why did the solution conduct again when more barium hydroxide was added after the endpoint?

Find more resources

  • Investigate the energy changes that happen in neutralisation reactions with this microscale experiment.  
  • Use this CPD article on acids and bases to overcome common misonceptions your learners may have. 
  • Read these 5 ways to explain titration and provide the scaffold to help your learners with titration calculations. 
  • Share the A future in chemistry: making the difference video with your learners to inspire and show them that chemistry is everywhere.
     

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Additional information

This resource is based on a worksheet originally created as part of the Practical Chemistry project, developed by the Nuffield Foundation and the Royal Society of Chemistry.