Chemistry 5070 · O Level · Acid–base titrations

Acid–base titrations — practice question

The mixture is a solid made from iron(II) sulfate and sand. A student finds the percentage by mass of iron(II) sulfate in this mixture.
(a)[1]

Calculate the mass of mixture used in the experiment.

(b)[1]

Suggest how the student ensures that no iron(II) sulfate is left on the filter paper.

(c)[2]

Suggest how the student should ensure that all the aqueous iron(II) sulfate is moved from the conical flask to the volumetric flask.

(d)[1]

Name the additional piece of apparatus used alongside the pipette.

(e)[1]

State the colour change seen in the conical flask at the end-point of the titration.

(f)[4]

Use the diagrams to fill in the table and calculate the average volume of T.

(g)[1]

Calculate the number of moles of potassium manganate(VII) in the average volume of T used in the titration.

(h)[1]

Calculate the number of moles of $\text{FeSO}_4$ in $20.0\,\text{cm}^3$ of R.

(i)[1]

Calculate the number of moles of $\text{FeSO}_4$ present in $500\,\text{cm}^3$ of R.

(j)[1]

Calculate the mass of $\text{FeSO}_4$ contained in $500\,\text{cm}^3$ of R. $[M_r:\text{FeSO}_4, 152]$

(k)[1]

Use your answers to (a) and (j) to find the percentage by mass of $\text{FeSO}_4$ in the mixture.

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