O-LevelChemistryMetals & Reactivity5070/21 · May/June 2015 · Q58 Marks

The flow chart shows some reactions of copper(II) nitrate, Cu(NO3)2. black solid CuO(s) brown gas A colourless gas that relights a glowing splint B heat strongly Cu(NO3)2(s) dissolve in water Cu(NO3)2(aq) reagent X warm with NaOH(aq) and Al(s) green ppt CuCO3(s) colourless gas C light blue ppt D

(a)(i)When two moles of Cu(NO3)2 is heated strongly, two moles of CuO, four moles of A and one mole of B are made. Write the formula for B.[1]
(a)(ii)Construct the equation for the action of heat on Cu(NO3)2.[2]
(b)Aqueous copper(II) nitrate is warmed with aqueous sodium hydroxide and aluminium powder. Name C and D. C is D is[2]
(c)Suggest the name of reagent X and construct the ionic equation, with state symbols, for the formation of the green precipitate, CuCO3(s). name of reagent X ionic equation[3]

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Mark scheme

Marking points from the official mark scheme (May/June 2015). The mark or mark type is shown in brackets.

[1] (a) (i) B is O2 (1)
[1] (a) (ii) 2Cu(NO3)2 → 2CuO + 4NO2 + O2 Identification of NO2 as a product (1) Balanced equation (1)
[1] (b) C is ammonia (1) D is copper(II) hydroxide (1)
[1] (c) Any soluble carbonate e.g. sodium carbonate/potassium carbonate/ammonium carbonate (1) Cu²⁺(aq) + CO3²⁻(aq) → CuCO3(s) Correct formulae (1) State symbols – dependent on formulae (1)

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