Stoichiometry Structured Questions | Cambridge O Level Chemistry

Question 1 of 7 · 10 marks

Stoichiometry · Reacting Masses & Limiting Reagent Curve

4 parts

Chemistry 5070 · Question 1[10 marks]

Magnesium metal reacts with dilute sulfuric acid to form aqueous magnesium sulfate and hydrogen gas:

Mg(s) + $\ce{H2SO4(aq)}$ → $\ce{MgSO4(aq)}$ + $\ce{H2(g)}$

A student adds increasing masses of magnesium ribbon to fixed 50.0 cm³ portions of dilute sulfuric acid and records the mass of anhydrous $\ce{MgSO4}$ recovered after evaporating to dryness. The yield graph levels off at Point X (0.96 g Mg added, yielding 4.80 g $\ce{MgSO4}$ ).

(a)

Explain why the mass of $\ce{MgSO4}$ does not increase beyond Point X.

[2]

(b)

Calculate the concentration of the dilute sulfuric acid used in mol dm⁻³.

[3]

(c)

Calculate the volume of hydrogen gas evolved at r.t.p. at Point X in cm³.

[2]

(d)

In a second experiment, 1.50 g of magnesium is added to 50.0 cm³ of the same acid. Calculate the mass of unreacted magnesium remaining.

[3]