Hydrogen peroxide, $$\(\mathrm{H}_{2} \mathrm{O}_{2}\)$$, reacts rapidly with acidified potassium manganate(VII), $$\(\mathrm{KMnO}_{4}\)$$. $$\[ 5 \mathrm{H}_{2} \mathrm{O}_{2}(\mathrm{aq})+2 \mathrm{MnO}_{4}^{-}(\mathrm{aq})+6 \mathrm{H}^{+}(\mathrm{aq}) \rightarrow 5 \mathrm{O}_{2}(\mathrm{~g})+8 \mathrm{H}_{2} \mathrm{O}(\mathrm{l})+2 \mathrm{Mn}^{2+}(\mathrm{aq}) \]$$ You will determine the concentration of a solution of hydrogen peroxide. You will first dilute the solution and then carry out a titration with acidified potassium manganate(VII). FA 1 is aqueous hydrogen peroxide, $$\(\mathrm{H}_{2} \mathrm{O}_{2}\)$$. FA 2 is $$\(0.0300 \mathrm{~mol} \mathrm{dm}^{-3}\)$$ potassium manganate(VII), $$\(\mathrm{KMnO}_{4}\)$$. FA 3 is $$\(1.0 \mathrm{~mol} \mathrm{dm}^{-3}\)$$ sulfuric acid, $$\(\mathrm{H}_{2} \mathrm{SO}_{4}\)$$.

Chemistry
IGCSE&ALevel
CAIE
Exam No:9701_s25_qp_33 Year:2025 Question No:1(a)

Answer:



Knowledge points:

2.2.1 define and use the term mole in terms of the Avogadro constant
2.4.1.1 reacting masses (from formulae and equations) including percentage yield calculations
2.4.1.2 volumes of gases (e.g. in the burning of hydrocarbons)
2.4.1.3 volumes and concentrations of solutions
2.4.1.4 limiting reagent and excess reagent (When performing calculations, candidates’ answers should reflect the number of significant figures given or asked for in the question. When rounding up or down, candidates should ensure that significant figures are neither lost unnecessarily nor used beyond what is justified (see also Mathematical requirements section).) deduce stoichiometric relationships from calculations such as those in 2.4.1 (1)–(4)
6.1.1 calculate oxidation numbers of elements in compounds and ions
6.1.2 use changes in oxidation numbers to help balance chemical equations
6.1.3 explain and use the terms redox, oxidation, reduction and disproportionation in terms of electron transfer and changes in oxidation number
6.1.4 explain and use the terms oxidising agent and reducing agent
6.1.5 use a Roman numeral to indicate the magnitude of the oxidation number of an element

Solution:

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