Chemistry · Oct / Nov 2020 · Paper 42 · Question 2
0620
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The question as text
Soluble salts can be made by adding a metal carbonate to a dilute acid.
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2(a)[1]
HNO3
2(b)(i)[1]
to make sure all the (sulfuric) acid reacts
2(b)(ii)[2]
no (more) fizzing (1)
(FeCO3) stops dissolving or a solid remains / is visible (in the mixture) (1)
2(b)(iii)[1]
rinse the residue (with distilled water)
2(b)(iv)[2]
a solution that can dissolve no more solute (1)
at the specified temperature (1)
2(b)(v)[1]
iron(II) oxide / iron(II) hydroxide
2(c)[3]
mass of FeSO4 = 152 (1)
mass of H2O = 278 – 152 = 126 (1)
mol of H2O = 126 / 18 and x = 7 (1)
2(d)(i)[1]
precipitation
2(d)(ii)[1]
cream precipitate
2(d)(iii)[3]
Ag+(aq) + Br–(aq) → AgBr(s)
AgBr (as only product) (1)
Ag+ and Br– (as reactants)(1)
state symbols(1)
2(e)[3]
M1 mol of NaCl = 2.34 / 58.5 = 0.04(00)
M2 mol of Cl 2 = M1/2 = 0.04(00)/2 = 0.02(00)
M3 0.02(00) × 24000 = 480 (cm3)
2(f)(i)[3]
ions (1)
(ions) are fixed (in a lattice) (1)
ions are mobile (1)
2(f)(ii)[1]
chlorine
2(f)(iii)[2]
oxidation (1)
electrons are lost (1)
2(f)(iv)[1]
dissolve it (in water)
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