RP1b: Carrying out an acid-base titration

What equipment should be rinsed before starting a titration? (3)

- Burette with acid

- Pipette with alkali

- Conical flask with distilled water

What volume of alkali is pipetted into the conical flask for titration? (1)

25 cm³

How should the burette be prepared before starting the titration? (2)

- Fill the burette with acid

- Ensure the jet space in the burette is filled with acid

What is recorded before starting the titration? (1)

The initial burette reading

What is added to the alkali in the conical flask before titration begins? (1)

A few drops of indicator

Why is a white tile placed underneath the conical flask during titration? (1)

To help observe the colour change

How is the acid added to the alkali in the conical flask? (2)

- Add acid whilst swirling the mixture

- Add acid dropwise near the endpoint

When should the titration be stopped? (1)

When the relevant colour change is observed

What is recorded at the end of the titration? (1)

The final burette reading

How many titrations should be performed to obtain concordant results? (1)

At least two concordant results (two readings within 0.1 cm³ of each other)

Why must the jet space in the burette be properly filled? (1)

If not filled, it will result in a larger than expected titration reading

Why are conical flasks preferred over beakers for titrations? (1)

They are easier to swirl

Why should only a few drops of indicator be used? (1)

Indicators are weak acids, so using too much affects the titration result

What is the colour change for phenolphthalein in titration? (2)

Alkali: Pink

Acid: Colourless (endpoint: pink colour just disappears)

What is the colour change for methyl orange in titration? (3)

Alkali: Yellow

Acid: Red

Endpoint: Orange

Draw and label a diagram of the apparatus used in this experiment (3)