M2S12 – Redox Reactions

The oxidation number of sulfur in sulfuric acid, H₂SO₄, is:

The oxidation number of vanadium in the VO²⁺ ion is:

The amount in moles of iodide ions oxidised by one mole of chlorine molecules is:

In the half equation: MnO₄^- _(aq) + 8H⁺_(aq) + ne^- -> Mn²⁺_(aq) + 4H₂O_(l) the value of n is:

Which of these changes are redox reactions?

(i) NaCl_(s) + H₂SO_4(l) -> HCl_(g) + NaHSO_4(s)

(ii) NH_3(g) + HCl_(g) -> NH₄Cl_(s)

(iii) CaCO_3(s) -> CaO_(s) + CO_2(g)

(iv) 2HBr_(g) + H₂SO_4 (l) -> Br_2(l) + SO_2(g) + 2H₂O_(l)

Hydrogen is oxidised when it reacts with:

(i) oxygen to form water

(ii) nitrogen to form ammonia

(iii) chlorine to form hydrogen chloride

(iv) sodium to form sodium hydride

In which of the following industrial conversions is a chemical species (atoms, molecule or ion) oxidised to give the element:

(i) iron ore oxide to iron

(ii) potassium iodate(V) to iodine

(iii) copper(II) sulfate to copper

(iv) sodium chloride to chlorine

In which of these reactions is the first named element reduced:

(i) hydrogen reacting with copper(II) oxide to form copper and water

(ii) iodine reacting with chlorine to form iodine monochloride

(iii) aluminium reacting with chromium(III) oxide to form aluminium(III) oxide and chromium

(iv) iodine reacting with aluminium to form aluminium iodide

Which of these conversions are reductions?

(i) CrO₄^2- to Cr₂O₇^2-

(ii) CrO₄^2- to Cr³⁺

(iii) CrO₄^2- to CrO₃

(iv) CrO₃ to Cr₂O₃

What mass of silver is displaced from aqueous silver nitrate solution by 4.00 g magnesium?

(Relative atomic masses: Mg = 24.3, Ag = 108)