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Acids, alkalis and titrations

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Question 51

An environmental chemist carries out a titration to determine the concentration of a sample of dilute nitric acid (HNO3\text{HNO}_3HNO3​).

This is the chemist's method:

  • pipette 20.0 cm320.0\text{ cm}^320.0 cm3 of the nitric acid into a conical flask
  • add a few drops of a suitable indicator
  • add aqueous sodium hydroxide (NaOH\text{NaOH}NaOH) from a burette until the end point is reached
  • record the volume of alkali added from the burette

The concentration of the sodium hydroxide solution used is 0.0250 mol/dm30.0250\text{ mol/dm}^30.0250 mol/dm3. The mean volume of sodium hydroxide required to neutralise the acid is 18.80 cm318.80\text{ cm}^318.80 cm3.

The equation for the reaction is:

HNO3+NaOH→NaNO3+H2O \text{HNO}_3 + \text{NaOH} \rightarrow \text{NaNO}_3 + \text{H}_2\text{O} HNO3​+NaOH→NaNO3​+H2​O
a.

Calculate the amount, in moles, of NaOH\text{NaOH}NaOH used in this titration.

[2]
b.

Calculate the concentration, in mol/dm3\text{mol/dm}^3mol/dm3, of the nitric acid.

[2]
c.

The chemist wishes to obtain a solid sample of the salt produced. Describe how they could use crystallisation to obtain a pure, dry sample of sodium nitrate crystals from the neutralised solution.

[4]

Acids, alkalis and titrations Questions

  1. IGCSE
  2. /Chemistry
  3. /Acids, alkalis and titrations