(a)(i) Describe briefly how trioxonitrate (V) ions could be tested for in the laboratory.
(ii) State two uses of each of the following compounds: I. sodium chloride; II. sodium trioxocarbonate (IV).
(b) Write balanced equations for the reactions involved in the extraction of iron in the blast furnace.
(ii) State Faraday's first law of electrolysis.
(iii) State two applications of electrolysis.
(c) Concentrated tetraoxosulphate (VI) acid is added to sugar crystals in a beaker. State what would be observed. Explain briefly your answer.
(d) Write an equation for the reaction of zinc powder with:
(i) dilute tetraoxosulphate (VI) acid;
(ii) concentrated tetraoxosulphate (VI) acid.
(e) What property of concentrated tetraoxosulphate (VI) acid is shown in (d)(ii)
(a)(i) Test for trioxonitrate(V) (nitrate) ion - brown ring test: add freshly prepared iron(II) sulphate solution to the test solution, then carefully pour concentrated tetraoxosulphate(VI) acid down the side of the tube so it forms a layer below. A brown ring forms at the junction of the two liquids.
(ii)
- I. Sodium chloride: seasoning/preserving food; raw material for making chlorine, sodium hydroxide and sodium trioxocarbonate(IV).
- II. Sodium trioxocarbonate(IV): softening hard water; manufacture of glass and soap.
(b)(i) Extraction of iron in the blast furnace
\[C + O_2 \rightarrow CO_2\]
\[CO_2 + C \rightarrow 2CO\]
\[Fe_2O_3 + 3CO \rightarrow 2Fe + 3CO_2\]
\[CaCO_3 \rightarrow CaO + CO_2\]
\[CaO + SiO_2 \rightarrow CaSiO_3 \text{ (slag)}\]
(ii) Faraday's first law: the mass of a substance liberated or deposited at an electrode during electrolysis is directly proportional to the quantity of electricity (charge) passed through the electrolyte.
(iii) Applications: electroplating; purification (refining) of metals; extraction of reactive metals.
(c) The white sugar turns black (a spongy black mass of carbon rises up), with much heat and steam given off. Concentrated tetraoxosulphate(VI) acid is a powerful dehydrating agent: it removes hydrogen and oxygen from the sucrose as water, leaving carbon:
\[C_{12}H_{22}O_{11} \xrightarrow{conc.\ H_2SO_4} 12C + 11H_2O\]
(d)(i) \[Zn + H_2SO_4\ (dilute) \rightarrow ZnSO_4 + H_2\]
(ii) \[Zn + 2H_2SO_4\ (conc.,\ hot) \rightarrow ZnSO_4 + SO_2 + 2H_2O\]
(e) In (d)(ii) the concentrated acid acts as an oxidizing agent.
(a)(i) Test for trioxonitrate(V) (nitrate) ion - brown ring test: add freshly prepared iron(II) sulphate solution to the test solution, then carefully pour concentrated tetraoxosulphate(VI) acid down the side of the tube so it forms a layer below. A brown ring forms at the junction of the two liquids.
(ii)
- I. Sodium chloride: seasoning/preserving food; raw material for making chlorine, sodium hydroxide and sodium trioxocarbonate(IV).
- II. Sodium trioxocarbonate(IV): softening hard water; manufacture of glass and soap.
(b)(i) Extraction of iron in the blast furnace
\[C + O_2 \rightarrow CO_2\]
\[CO_2 + C \rightarrow 2CO\]
\[Fe_2O_3 + 3CO \rightarrow 2Fe + 3CO_2\]
\[CaCO_3 \rightarrow CaO + CO_2\]
\[CaO + SiO_2 \rightarrow CaSiO_3 \text{ (slag)}\]
(ii) Faraday's first law: the mass of a substance liberated or deposited at an electrode during electrolysis is directly proportional to the quantity of electricity (charge) passed through the electrolyte.
(iii) Applications: electroplating; purification (refining) of metals; extraction of reactive metals.
(c) The white sugar turns black (a spongy black mass of carbon rises up), with much heat and steam given off. Concentrated tetraoxosulphate(VI) acid is a powerful dehydrating agent: it removes hydrogen and oxygen from the sucrose as water, leaving carbon:
\[C_{12}H_{22}O_{11} \xrightarrow{conc.\ H_2SO_4} 12C + 11H_2O\]
(d)(i) \[Zn + H_2SO_4\ (dilute) \rightarrow ZnSO_4 + H_2\]
(ii) \[Zn + 2H_2SO_4\ (conc.,\ hot) \rightarrow ZnSO_4 + SO_2 + 2H_2O\]
(e) In (d)(ii) the concentrated acid acts as an oxidizing agent.
