New
New
Year 10
OCR
Higher

Titrations: making soluble salts

I can accurately perform a titration, understanding the apparatus and selecting a suitable indicator to identify the end point.

New
New
Year 10
OCR
Higher

Titrations: making soluble salts

I can accurately perform a titration, understanding the apparatus and selecting a suitable indicator to identify the end point.

Lesson details

Key learning points

  1. Titration is a method used to completely neutralise an acid with a soluble base (alkali).
  2. Titrations are performed using strong acids and strong alkalis to accurately determine reacting volumes.
  3. Strong acids and alkalis are completely ionised in an aqueous solution.
  4. Each piece of apparatus in a titration has a specific and essential function.
  5. A suitable indicator (not universal indicator) is used to identify the end point of the titration.

Common misconception

Pupils often overshoot the end point, especially on their first attempt at a titration.

Pupils will need to work on their dexterity, often with a partner, to ensure the flow of titrant is slow enough from the burette, and that their swirling technique allows ample mixing of the solutions.

Keywords

  • Titration - a technique in volumetric analysis that is used to find the exact volumes of solutions that react with each other

  • Volume - how much 3D space matter occupies, it is often measured in cm³

  • End point - when just enough solution has been added from the burette to react with all the solution in the flask in a titration

  • Strong acid - strong acids ionise completely in water.

  • Meniscus - the curve that exists on the surface of a liquid when it is in a container

Ensure you have plenty of all reactants and conical flasks, to allow pupils multiple attempts at a titration.
Teacher tip

Equipment

burettes, volumetric pipettes/measuring cylinders, mini funnels, conical flasks, 0.1 M solutions of HCl and NaOH, white tiles, pipette fillers, phenolphthalein indicator

Content guidance

  • Risk assessment required - chemicals
  • 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).

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6 Questions

Q1.
What is the process of neutralisation?
Diluting an acid with water to make it weaker.
Mixing an acid with a solid to release heat.
Correct answer: Reacting an acid with a base to form water and a salt.
Combining two acids to form a stronger one.
Q2.
What is a characteristic of strong acids and alkalis?
They dissolve only slightly in water.
They are always more concentrated than weak acids and alkalis.
They cannot be neutralised by a base or acid.
Correct answer: They are completely ionised in water.
Q3.
What is the difference between the concentration and strength of an acid?
Strength and concentration are the same thing.
Strength refers to how much acid is dissolved in water.
Correct answer: Strength is how easily an acid ionises in water.
Correct answer: Concentration refers to how much acid is dissolved in water.
Concentration is how easily an acid ionises in water.
Q4.
What happens when an acid reacts with a soluble base (alkali) in a neutralisation reaction?
Correct answer: A salt and water are formed.
Only a gas is produced.
Only water is produced.
The acid becomes more concentrated.
Q5.
Why might you use an indicator in a neutralisation reaction between an acid and a base?
Correct answer: To show when the acid and base have reacted completely.
To speed up the reaction.
To change the colour of the solution permanently.
To make the acid stronger.
Q6.
What is the most accurate way to measure the volume of a liquid?
Use a spoon to add small amounts at a time.
Estimate the volume by eye.
Pour the liquid into a measuring jug.
Correct answer: Use a piece of equipment that allows precise control over the amount of liquid.

6 Questions

Q1.
Match each piece of apparatus used in titration to its correct function.
Correct Answer:burette,Measures and dispenses precise volumes of acid or alkali.

Measures and dispenses precise volumes of acid or alkali.

Correct Answer:volumetric pipette,Transfers a fixed volume of solution to the conical flask.

Transfers a fixed volume of solution to the conical flask.

Correct Answer:conical flask,Holds the solution being titrated.

Holds the solution being titrated.

Correct Answer:indicator,Shows when neutralisation is complete.

Shows when neutralisation is complete.

Q2.
Sort the steps of performing a titration into the correct order.
1 - Use a volumetric pipette to add a fixed volume of alkali to the flask.
2 - Add a few drops of indicator to the solution in the flask.
3 - Fill the burette with acid and record the starting volume.
4 - Slowly add acid, drop-by-drop near the end point, whilst swirling the flask.
5 - Stop when the indicator changes colour permanently, indicating neutralisation.
6 - Record the final volume of acid in the burette.
7 - Calculate the volume of acid added.
Q3.
Why is titration used in chemistry?
Correct answer: To accurately measure the volume of acid or alkali needed for neutralisation.
To determine how strong an acid or alkali is.
To heat up acids and bases to their boiling points.
To identify the type of salt produced in a reaction.
Q4.
Which of the following statements describes strong acids and alkalis, used in titrations, most accurately?
They only partially ionise in water.
They are always very concentrated solutions.
Correct answer: They are completely ionised in an aqueous solution.
They neutralise each other without producing any products.
Q5.
Why is a suitable indicator (not universal indicator) used in titration?
It changes colour gradually to show progress.
It neutralises the acid and alkali.
It speeds up the reaction between the acid and alkali.
Correct answer: It provides a sharp colour change at the end point of the reaction.
Q6.
Why are strong acids and strong alkalis used in titrations?
Correct answer: To ensure that the reaction reaches completion and all ions are used.
To make the titration process faster.
Because strong acids and alkalis are safer to handle.
To produce a more concentrated salt solution.

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