Chemistry · May / June 2023 · Paper 42 · Question 4
0620
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The question as text
Solid sodium hydroxide is a base which dissolves to form an aqueous solution, NaOH(aq).
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4(a)[1]
proton acceptor
4(b)[1]
alkali
4(c)[1]
blue
4(d)[3]
M1 sodium chloride
M2 water
M3 ammonia
4(e)(i)[1]
amphoteric (oxides)
4(e)(ii)[1]
aluminium oxide
or
zinc oxide
4(f)(i)[3]
M1 all single bonding dot and cross pairs correct
M2 double C = O bond dot and cross pairs are correct
M3 complete diagram is correct
4(f)(ii)[1]
3≤ pH < 7
CH3COOH ⇌ CH3COO– + H+
4(f)(iii)[3]
M3 use of ⇌
M1 H+
M2 CH3COO–
4(f)(iv)[1]
H+ + OH– → H2O
4(g)[5]
M1 mol KOH = 0.0800 × 25 / 1000
= 0.002(00) / 2(00) × 10–3
M2 mol H2SO4 = M1 / 2 = 0.002 / 2
= 0.001(00) / 1(00 × 10–3
M3 = M2 × 1000 / 20 = 0.001 × 1000 / 20
= 0.05(00) / 5.(00) × 10–2
M4 = 98
M5 = 98 × M3 = 98 × 0.05(00) = 4.9(0) (g / dm3)
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