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Chemical Changes

Carrying out an acid-alkali titration

  • 2 things to know
  • Paper 3

Overview

Using a pipette, burette and phenolphthalein, adding acid drop by drop near the end point, concordant results, making a pure salt, and accuracy, precision, repeatability, random and systematic errors and the uncertainty in a mean titre.

What you need to know

Answer each one before you reveal it.

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Key term

Name the apparatus used to measure an accurate fixed volume of alkali into a conical flask for a titration.

Key term

Name the apparatus used to add acid a little at a time during a titration.

Questions from this subtopic

Each one with the model answer underneath.

  1. 1

    Name the apparatus used to measure an accurate fixed volume of alkali into a conical flask for a titration.

    Model answer

    A pipette, used with a pipette filler, measures the fixed volume.

  2. 2

    Name the apparatus used to add acid a little at a time during a titration.

    Model answer

    A burette is used to add the acid.

  3. 3

    Name a suitable indicator for a titration between an acid and an alkali.

    Model answer

    Phenolphthalein is a suitable indicator.

  4. 4

    Describe the colour change of phenolphthalein at the end point when acid is run into an alkali.

    Model answer

    The solution changes from pink to colourless.

  5. 5

    Explain why acid is added drop by drop near the end point of a titration.

    Model answer

    A single drop can take the mixture past neutralisation, so the exact volume would be overshot.

  6. 6

    Explain why a titration is repeated until concordant results are obtained.

    Model answer

    Repeating and averaging closely agreeing results makes the measured volume more reliable.

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States of Matter and Mixtures
Chemical Changes
Extracting Metals and Equilibria

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