Self Assess 1.3 (Textbook) – Chemistry Form 5 Chapter 1 (Redox Equilibrium)

Question 1:
Write the cell notation for the following voltaic cells:

\begin{aligned} {S n}^{2 +} / S n and {M g}^{2 +} / M g . \\ {C l}_{2} / {C l}^{-} and {M n O}_{4}^{-} / {M n}^{2 +} . \end{aligned}

$\begin{aligned} & \mathrm{Sn}^{2+} / \mathrm{Sn} \text { and } \mathrm{Mg}^{2+} / \mathrm{Mg} . \\ & \mathrm{Cl}_2 / \mathrm{Cl}^{-} \text {and } \mathrm{MnO}_4^{-} / \mathrm{Mn}^{2+} . \end{aligned}$
Answer:
(a)

Mg (s) | {M g}^{2 +} (a q) | | {S n}^{2 +} (a q) | Sn (s)

$\operatorname{Mg}(\mathrm{s})\left|\mathrm{Mg}^{2+}(\mathrm{aq})\right|\left|\mathrm{Sn}^{2+}(\mathrm{aq})\right| \operatorname{Sn}(\mathrm{s})$

(b)

Pt (s) | {C l}^{-} (a q), {C l}_{2} (a q) | | {M n O}_{4}^{-} (a q), {M n}^{2 +} (a q) | Pt (s)

$\operatorname{Pt}(\mathrm{s})\left|\mathrm{Cl}^{-}(\mathrm{aq}), \mathrm{Cl}_2(\mathrm{aq})\right|\left|\mathrm{MnO}_4^{-}(\mathrm{aq}), \mathrm{Mn}^{2+}(\mathrm{aq})\right| \operatorname{Pt}(\mathrm{s})$

Question 2:
Calculate the voltage for the following cells:

(a) N i (s) | {N i}^{2 +} (a q) ‖ {P b}^{2 +} (a q) | P b (s) .

$\text { (a) } \mathrm{Ni}(\mathrm{s})\left|\mathrm{Ni}^{2+}(\mathrm{aq}) \| \mathrm{Pb}^{2+}(\mathrm{aq})\right| \mathrm{Pb}(\mathrm{s}) \text {. }$

(b) Pt (s) | I^{-} (a q), I_{2} (a q) ‖ {A g}^{+} (a q) | Ag (s) .

$\text { (b) } \operatorname{Pt}(\mathrm{s})\left|\mathrm{I}^{-}(\mathrm{aq}), \mathrm{I}_2(\mathrm{aq}) \| \mathrm{Ag}^{+}(\mathrm{aq})\right| \operatorname{Ag}(\mathrm{s}) \text {. }$

(c) P t (s) | {F e}^{2 +} (a q), {F e}^{3 +} (a q) ‖ {A g}^{+} (a q) | A g (s) .

$\text { (c) } \mathrm{Pt}(\mathrm{s})\left|\mathrm{Fe}^{2+}(\mathrm{aq}), \mathrm{Fe}^{3+}(\mathrm{aq}) \| \mathrm{Ag}^{+}(\mathrm{aq})\right| \mathrm{Ag}(\mathrm{s}) \text {. }$

(d) Pt (s) | {B r}^{-} (a q), {B r}_{2} (a q) ‖ {C l}_{2} (a q), {C l}^{-} (a q) | Pt (s) .

$\text { (d) } \operatorname{Pt}(\mathrm{s})\left|\mathrm{Br}^{-}(\mathrm{aq}), \mathrm{Br}_2(\mathrm{aq}) \| \mathrm{Cl}_2(\mathrm{aq}), \mathrm{Cl}^{-}(\mathrm{aq})\right| \operatorname{Pt}(\mathrm{s}) \text {. }$

Jawapan:
(a)

E_{cell}^{0} = (+ 0.13) - (- 0.25) = + 0.12 V

$\mathrm{E}_{\text {cell}}^0=(+0.13)-(-0.25)=+0.12 \mathrm{~V}$

(b)

E_{cell}^{0} = (+ 0.80) - (+ 0.54) = + 0.26 V

$\mathrm{E}_{\text {cell }}^0=(+0.80)-(+0.54)=+0.26 \mathrm{~V}$

(c)

E_{cell}^{0} = (+ 0.80) - (+ 0.77) = + 0.03 V

$\mathrm{E}_{\text {cell }}^0=(+0.80)-(+0.77)=+0.03 \mathrm{~V}$

(d)

E_{cell}^{0} = (+ 1.36) - (+ 1.07) = + 0.29 V

$\mathrm{E}_{\text {cell }}^0=(+1.36)-(+1.07)=+0.29 \mathrm{~V}$

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