Chemistry 5070 · O Level · Acid–base titrations

Acid–base titrations — practice question

‘Lawn sand’ consists of sand combined with iron(II) sulfate and ammonium sulfate, and it is used to encourage grass growth.
(a)[1]

Calculate the mass of $L$ that was used in the experiment.

(b)[1]

How could the sand be taken out of the mixture?

(c)[1]

What is the colour of the solution in the conical flask before $P$ has been added and after $P$ is just in excess?

(d)[4]

Use the diagrams to fill in the table and calculate the mean volume of $P$ used.

(e)[1]

Calculate the number of moles of potassium manganate(VII) in the mean volume of $P$.

(f)[1]

Calculate the number of moles of $\text{Fe}^{2+}$ present in $25.0\,\text{cm}^3$ of $M$.

(g(i))[1]

Calculate the number of moles of $\text{Fe}^{2+}$ present in $250\,\text{cm}^3$ of $M$.

(g(ii))[1]

Calculate the mass of iron in $250\,\text{cm}^3$ of $M$.

(h)[1]

Calculate the percentage by mass of iron in $L$.

(i(i))[2]

Calculate the percentage by mass of nitrogen in $(\text{NH}_4)_2\text{SO}_4$.

(i(ii))[1]

Name one other compound that can be used as a nitrogenous fertiliser.

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