Chemistry 9701 · AS & A Level · 2.1

2.1 — practice question

Manganese, Mn, and its compounds are used extensively in a broad range of chemical reactions.
(a(i))[1]

Determine the numbers of protons, neutrons and electrons in one atom of manganese-55.

(a(ii))[1]

Define isotopes in terms of atomic structure.

(a(iii))[2]

A sample of manganese from the Moon is discovered to contain manganese-53 as well as manganese-55. State the two pieces of information needed to determine the relative atomic mass, $A_r$, of manganese in this sample.

(b(i))[1]

Complete the full electronic configuration of manganese from the shorthand configuration $[\mathrm{Ar}]\,3d^5\,4s^2$.

(b(ii))[1]

Deduce the total number of unpaired electrons in one atom of manganese.

(c(i))[1]

Manganese(IV) oxide reacts with methanal, $\mathrm{CH_2O}$, under acidic conditions to form carbon dioxide. Electron transfer to or from the relevant species is shown in the half-equations below: Half-equation 1: $\mathrm{CH_2O + H_2O \rightarrow CO_2 + 4H^+ + 4e^-}$; Half-equation 2: $\mathrm{MnO_2 + 4H^+ + 2e^- \rightarrow Mn^{2+} + 2H_2O}$. Identify the species that is reduced in half-equation 2. Explain your answer.

(c(ii))[1]

Given that carbon in methanal has oxidation state 0, Calculate the oxidation state of carbon in carbon dioxide.

(c(iii))[2]

Construct the ionic equation for the reaction of manganese(IV) oxide with methanal in acidic conditions.

Worked solution & mark scheme

This 10-mark question has a full step-by-step worked solution and mark scheme. One marking point: 25 protons, 30 neutrons and 25 electrons

  • Full mark scheme, point by point
  • Step-by-step worked solution
  • Write your answer & get it marked instantly by AI