levo

Acid-Base Titrations

Indicators and the end point

  • 3 things to know
  • Unit AS 1

Overview

End point of a titration, colours of phenolphthalein in acid and in alkali and colours of methyl orange in acid and in alkali.

What you need to know

Answer each one before you reveal it.

Your recallNot started
Key term

Distinguish between the end point and the equivalence point of a titration.

Key term

What is meant by the end point of a titration?

Key term

Why is only a few drops of indicator added to the conical flask?

Questions from this subtopic

Each one with the model answer underneath.

  1. 1

    What is meant by the end point of a titration?

    Model answer

    The end point is the moment at which the indicator changes colour permanently, marking the completion of the reaction.

  2. 2

    Why is only a few drops of indicator added to the conical flask?

    Model answer

    An indicator is itself a weak acid or base, so adding more than a few drops would react with a measurable amount of the solution being titrated.

  3. 3

    State the colours of phenolphthalein in acid and in alkali.

    Model answer

    Phenolphthalein is colourless in acid and pink in alkali.

  4. 4

    State the colours of methyl orange in acid and in alkali.

    Model answer

    Methyl orange is red in acid and yellow in alkali.

  5. 5

    Describe the colour seen at the end point when methyl orange is used.

    Model answer

    The solution turns from yellow to the first permanent orange as the acid is added.

  6. 6

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

    Model answer

    The colourless solution turns to the first permanent pale pink.

Other ways to work this

The same content, four other ways.

What is inside Levo

Six ways to work the same material.

1Closed book
2Open book
3Closed book

The 3-step method, run for you

Answer cold, learn it, then prove it stuck. Levo tracks the jump between your first attempt and your last.

Formulae, Equations and Amounts of Substance
Atomic Structure
Bonding
Intermolecular Forces and Structure

Cram a whole paper in one sitting

Sort every topic into what you know and what you do not, then drill only the weak ones.

Yellow to .
brownbluegreen

Blank Blitz makes facts automatic

Rapid timed gap-fills on the terms and numbers you need to recall without thinking.

AThe reactants total 159.6 + 84.0 = 243.6.
BThe two moles of iron have a mass of 111.6.
CThe atom economy is 45.8%.

Build It gets the exam shape right

Assemble a full-mark answer from its marking points, in the order an examiner wants them.

There are 1000 cm³ in one dm³.
TrueFalse

Test It catches misconceptions

Spot the fault in a statement. The traps are the mistakes students actually make.

721941163128510

Brain Breaks between sessions

Short focus games to reset attention, so the next set lands better than the last.

Every question in Acid-Base Titrations, on a schedule.

Attempt a question from memory, write the correct version, then attempt it again. Levo records the jump between your first attempt and your last, and brings each question back on the day you are due to forget it.

Or £46 a year, about £3.83 a month. Cancel anytime.