O-LevelChemistryMetals & Reactivity5070/21 · May/June 2016 · Q58 Marks

The statements give some of the chemical properties of metal X and its compounds. • X does not react with cold water. • X fizzes slowly with dilute hydrochloric acid. • X does not react with aqueous sodium chloride. • X reacts with aqueous lead(II) nitrate. • X reacts with aqueous silver nitrate. • XO reacts with magnesium to form X.

(a)Use the information to help arrange the following metals in order of reactivity. lead, magnesium, silver, sodium and X most reactive .................................................................................................................................................................................................. least reactive[2]
(b)Suggest a possible identity for X.[1]
(c)Construct the equation for the reaction between the oxide, XO, and magnesium.[1]
(d)Construct the ionic equation for the reaction between X and aqueous lead(II) nitrate, Pb(NO3)2(aq).[1]
(e)Metal X is a good electrical conductor and has a high melting point. Explain why X • conducts electricity, • has a high melting point.[3]

Mark scheme

Marking points from the official mark scheme (May/June 2016). The mark or mark type is shown in brackets.

[2] sodium magnesium X lead silver Sodium, magnesium, lead and silver in correct order (ignore X) (1) X directly between magnesium and lead (1)
[1] Zinc/iron/tin (1)
[1] XO + Mg → MgO + X (1)
[1] X + Pb²⁺ → X²⁺ + Pb (1)
[3] Conducts electricity Electrons can move (1) High melting point Attraction between sea of electrons and (positive) ions/forces between sea of electrons and ions (1) Attraction is very strong/force is very strong/it takes a lot of energy to overcome these strong forces (1) (this mark is dependent on attraction between (positive) ions and electrons/forces between ions and electrons)

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