Question

(i) Pb(NO₃)₂(aq) + 2KI(aq) → PbI₂(x) + 2KNO₃(y) (ii) Cu(s) + 2AgNO₃(aq) → Cu(NO₃)₂(aq) + x(s) (iii) Zn(s) + H₂SO₄(aq) → ZnSO₄(x) + H₂(y) (iv) CaCO₃(s) → x CaO(s) + CO₂(g)

September 7, 2024

Answer

(i) Pb(NO₃)₂(aq) + 2KI(aq) → PbI₂(𝑠) + 2KNO₃(𝑎𝑞)

x = s (solid, as PbI₂ precipitates)
y = aq (aqueous, since KNO₃ remains dissolved in water)

(ii) Cu(s) + 2AgNO₃(aq) → Cu(NO₃)₂(aq) + 2Ag(s)

x = Ag (solid silver precipitates)

(iii) Zn(s) + H₂SO₄(aq) → ZnSO₄(aq) + H₂(g)

x = aq (since ZnSO₄ dissolves in water)
y = g (since H₂ is a gas)

(iv) CaCO₃(s) → CaO(s) + CO₂(g)

x = CaO (solid calcium oxide)

So, the completed reactions are:

Pb(NO₃)₂(aq) + 2KI(aq) → PbI₂(s) + 2KNO₃(aq)
Cu(s) + 2AgNO₃(aq) → Cu(NO₃)₂(aq) + 2Ag(s)
Zn(s) + H₂SO₄(aq) → ZnSO₄(aq) + H₂(g)
CaCO₃(s) → CaO(s) + CO₂(g)

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