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

Question 1:
Write the cell notation for the following voltaic cells:
$$\begin{aligned} & \mathrm{Sn}^{2+} / \mathrm{Sn} \text { and } \mathrm{Mg}^{2+} / \mathrm{Mg} . \\ & \mathrm{Cl}_2 / \mathrm{Cl}^{-} \text {and } \mathrm{MnO}_4^{-} / \mathrm{Mn}^{2+} . \end{aligned}$$
Answer:
(a)
$$\operatorname{Mg}(\mathrm{s})\left|\mathrm{Mg}^{2+}(\mathrm{aq})\right|\left|\mathrm{Sn}^{2+}(\mathrm{aq})\right| \operatorname{Sn}(\mathrm{s})$$

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

Question 2:
Calculate the voltage for the following cells:
$$\text { (a) } \mathrm{Ni}(\mathrm{s})\left|\mathrm{Ni}^{2+}(\mathrm{aq}) \| \mathrm{Pb}^{2+}(\mathrm{aq})\right| \mathrm{Pb}(\mathrm{s}) \text {. }$$
$$\text { (b) } \operatorname{Pt}(\mathrm{s})\left|\mathrm{I}^{-}(\mathrm{aq}), \mathrm{I}_2(\mathrm{aq}) \| \mathrm{Ag}^{+}(\mathrm{aq})\right| \operatorname{Ag}(\mathrm{s}) \text {. }$$
$$\text { (c) } \mathrm{Pt}(\mathrm{s})\left|\mathrm{Fe}^{2+}(\mathrm{aq}), \mathrm{Fe}^{3+}(\mathrm{aq}) \| \mathrm{Ag}^{+}(\mathrm{aq})\right| \mathrm{Ag}(\mathrm{s}) \text {. }$$
$$\text { (d) } \operatorname{Pt}(\mathrm{s})\left|\mathrm{Br}^{-}(\mathrm{aq}), \mathrm{Br}_2(\mathrm{aq}) \| \mathrm{Cl}_2(\mathrm{aq}), \mathrm{Cl}^{-}(\mathrm{aq})\right| \operatorname{Pt}(\mathrm{s}) \text {. }$$


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

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

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

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