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Answer the following.
Answer the following: A solution of is diluted by adding water. What will happen to its specific…
Answer the following:
(a)[1.0]
A $0\cdot01\text{ M}$ solution of $\text{NaCl}$ is diluted by adding water. What will happen to its specific conductivity and molar conductivity?
(b)[1.0]
Is it safe to stir $1\text{M AgNO}_3$ solution with a copper spoon? Explain.
(Given: $E^\circ(\text{Cu}^{2+}/\text{Cu}) = +0\cdot34\text{ V}$, $E^\circ(\text{Ag}^+/\text{Ag}) = +0\cdot80\text{ V})$
(c)[1.0]
Two metals A and B have standard reduction potential values $-2\cdot37\text{ V}$ and $+0\cdot80\text{ V}$ respectively. Which of these will liberate $\text{H}_2$ gas from dil. $\text{HCl}$?
Answer
Answer (a)
Official answer keyOn dilution the specific conductivity (conductivity) decreases, because fewer ions are present per unit volume, while the molar conductivity increases, because $\Lambda_m = \kappa \times V_m$ and $V_m$ rises.
Answer (b)
Official answer keyEquation: $\mathrm{Cu} + 2\mathrm{Ag}^{+} \longrightarrow \mathrm{Cu}^{2+} + 2\mathrm{Ag}$
Formula used: Standard emf of a cell: E0cell = E0cathode - E0anode with E0anode = 0.34 V, E0cathode = 0.80 V, so E0cell = 0.46 V
No, it is not safe. $E^\circ_{cell} = E^\circ_{cathode} - E^\circ_{anode} = 0.80 - 0.34 = +0.46\ \mathrm{V}$, which is positive, so copper displaces silver and dissolves in $\mathrm{AgNO_3}$ solution.
Answer (c)
Official answer keyMetal A ($E^\circ = -2.37\ \mathrm{V}$) liberates $\mathrm{H_2}$ from dil. HCl, because a metal with a lower (more negative) reduction potential than hydrogen ($0.00\ \mathrm{V}$) is oxidised by $\mathrm{H^+}$.
From ISC 2026 Specimen Chemistry Paper 1, question 16(i).