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Acids, alkalis and titrations

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Question 49

An iron deficiency can be treated with iron tablets. A chemist wants to determine the percentage by mass of iron(II) ions (Fe2+\text{Fe}^{2+}Fe2+) in a brand of iron tablets.

She uses the following method:

  • Weighs an iron tablet.
  • Dissolves the tablet in an excess of dilute sulfuric acid.
  • Titrates the resulting solution with standardized potassium permanganate solution, KMnO4\text{KMnO}_4KMnO4​.

The table below shows her experimental results:

MeasurementValue
Mass of iron tablet0.350 g0.350\text{ g}0.350 g
Concentration of KMnO4\text{KMnO}_4KMnO4​ solution0.0150 mol/dm30.0150\text{ mol/dm}^30.0150 mol/dm3
Volume of KMnO4\text{KMnO}_4KMnO4​ solution added22.40 cm322.40\text{ cm}^322.40 cm3
a.

Calculate the amount, in moles, of KMnO4\text{KMnO}_4KMnO4​ in 22.40 cm322.40\text{ cm}^322.40 cm3 of 0.0150 mol/dm30.0150\text{ mol/dm}^30.0150 mol/dm3 potassium permanganate solution.

[2]
b.

In the titration, 1 mol1\text{ mol}1 mol of KMnO4\text{KMnO}_4KMnO4​ reacts with 5 mol5\text{ mol}5 mol of Fe2+\text{Fe}^{2+}Fe2+. Calculate the amount, in moles, of Fe2+\text{Fe}^{2+}Fe2+ in the iron tablet.

[2]
c.

Calculate the mass, in grams, of Fe2+\text{Fe}^{2+}Fe2+ in the iron tablet. [Ar of Fe=56.0A_{\text{r}}\text{ of Fe} = 56.0Ar​ of Fe=56.0]

[2]
d.

Calculate the percentage by mass of Fe2+\text{Fe}^{2+}Fe2+ in the iron tablet.

[2]

Acids, alkalis and titrations Questions

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