Calculate the valency factor of the following-i Ca - Ca 2-2 e -ii K - K - e -iii Mn 7-5 e - Mn 2-A- 2-1-5B- 1-3-7C- 2-1-7D- 1-2-5

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Standard XII

Chemistry

Equivalent Mass

Calculate the...

Question

Calculate the valency factor of the following:
(i) Ca $\to$ ${C a}^{2 +}$ + 2 $e^{-}$
(ii)K $\to$ $K^{+}$ + $e^{-}$
(iii) ${M n}^{7 +}$ + 5 $e^{-}$ $\to$ ${M n}^{2 +}$

2, 1, 7

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1, 2, 5

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2, 1, 5

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1, 3, 7

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Solution

The correct option is C
2, 1, 5

To find the valency factor, we need to look at the change in oxidation state; of the atom under consideration.
(i) Ca $\to$ ${C a}^{2 +}$ + 2 $e^{-}$
0 $\to$ +2 $\Rightarrow$ v.f = 2
(ii) K $\to$ $K^{+}$ + $e^{-}$
0 $\to$ +1 $\Rightarrow$ v.f = 1
(iii) ${M n}^{7 +}$ + 5 $e^{-}$ $\to$ ${M n}^{2 +}$

+7 $\to$ +2 $\Rightarrow$ v.f = 5

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Similar questions

Calculate the valency factor of the following:
(i) Ca $\to$ ${C a}^{2 +}$ + 2 $e^{-}$
(ii)K $\to$ $K^{+}$ + $e^{-}$
(iii) ${M n}^{7 +}$ + 5 $e^{-}$ $\to$ ${M n}^{2 +}$

Q. Calculate the value of

E_{M n O_{4}^{-} | M n O_{2}}^{\circ}

M n O_{4}^{-} + 8 H^{+} + 5 e^{-} \to M n^{2 +} + 4 H_{2} O

;

E^{\circ} = 1.51 V

M n O_{2} + 4 H^{+} + 2 e^{-} \to M n^{2 +} + 2 H_{2} O

;

E^{\circ} = 1.23 V

Identify the following reactions as either oxidation or reduction :

(i) $O + 2 e^{-} \to O^{2 -}$ (ii) $K - e^{-} \to K^{+}$ (iii) $F e^{3 +} + e^{-} \to F e^{2 +}$

Q. Find the

△ G^{\circ}

of a galvanic cell with

A g

and

A l

Standard Reduction Potentials at

25^{\circ} C

Half-Reaction	$E^{\circ} (V)$
$F_{2} + 2 e^{-} \to 2 F^{-}$	$2.87$
$A g^{2} + e^{-} \to A g^{+}$	$1.99$
$C o^{3 +} + e^{-} \to C o^{2 +}$	$1.82$
$H_{2} O_{2} + 2 H^{+} + 2 e^{-} \to 2 H_{2} O$	$1.78$
$M n O_{4}^{-} + 4 H^{+} + 3 e^{-} \to M n O_{2} + 2 H_{2} O$	$1.68$
$2 e^{-} + 2 H^{+} + I O_{4}^{-} \to I O_{3}^{-} + H_{2} O$	$1.60$
$M n O_{4}^{-} + 8 H^{+} + 5 e^{-} \to M n^{2 +} + 4 H_{2} O$	$1.51$
$A u^{3 +} + 3 e^{-} \to A u$	$1.50$
$C l_{2} + 2 e^{-} \to 2 C l^{-}$	$1.36$
$O_{2} + 4 H^{+} + 4 e^{-} \to 2 H_{2} O$	$1.23$
$M n O_{2} + 4 H^{+} + 2 e^{-} \to M n^{2 +} + 2 H_{2} O$	$1.21$
$B r_{2} + 2 e^{-} \to 2 B r^{-}$	$1.09$
$N O_{3}^{-} + 4 H^{+} + 3 e^{-} \to N O + 2 H_{2} O$	$0.96$
$C l O_{2} + e^{-} \to C l O_{2}$	$0.954$
$2 H g^{2 +} + 2 e^{-} \to H g_{2}^{2 +}$	$0.91$
$A g^{+} + e^{-} \to A g$	$0.80$
$H g_{2}^{2 +} + 2 e^{-} \to 2 H g$	$0.80$
$F e^{3 +} + e^{-} \to F e^{2 +}$	$0.77$
$O_{2} + 2 H^{+} + 2 e^{-} \to H_{2} O_{2}$	$0.68$
$M n O_{4}^{-} + e^{-} \to M n O_{4}^{2 -}$	$0.56$
$I_{2} + 2 e^{-} \to 2 I^{-}$	$0.54$
$C u^{+} + e^{-} \to C u$	$0.52$
$O_{2} + 2 H_{2} O + 4 e^{-} \to 4 O H^{-}$	$0.40$
$C u^{2 +} + 2 e^{-} \to C u$	$0.34$
$A g C l + e^{-} \to A g + C l^{-}$	$0.22$
$C u^{2 +} + e^{-} \to C u^{+}$	$0.16$
$2 H^{+} + 2 e^{-} \to H_{2}$	$0.00$
$F e^{3 +} + 3 e^{-} \to F e$	$- 0.036$
$P b^{2 +} + 2 e^{-} \to P b$	$- 0.13$
$N i^{2 +} + 2 e^{-} \to N i$	$- 0.23$
$C d^{2 +} + 2 e^{-} \to C d$	$- 0.40$
$F e^{2 +} + 2 e^{-} \to F e$	$- 0.44$
$C r^{3 +} + e^{-} \to C r^{2 +}$	$- 0.50$
$C r^{3 +} + 3 e^{-} \to C r$	$- 0.73$
$Z n^{2 +} + 2 e^{-} \to Z n$	$- 0.76$
$2 H_{2} O + 2 e^{-} \to H_{2} + 2 O H^{-}$	$- 0.83$
$M n^{2 +} + 2 e^{-} \to M n$	$- 1.18$
$A l^{3 +} + 3 e^{-} \to A l$	$- 1.66$
$H_{2} + 2 e^{-} \to 2 H^{-}$	$- 2.23$
$M g^{2 +} + 2 e^{-} \to M g$	$- 2.37$
$N a^{+} + e^{-} \to N a$	$- 2.71$
$C a^{2 +} + 2 e^{-} \to C a$	$- 2.76$
$B a^{2 +} + 2 e^{-} \to B a$	$- 2.90$
$K^{+} + e^{-} \to K$	$- 2.92$
$L i^{+} + e^{-} \to L i$	$- 3.05$

Q. Rank the following elements by increasing ease of oxidation with most easily oxidized LAST:

C d, C u, N i, F e

Standard Reduction Potentials at

25^{\circ} C

Half-Reaction	$E^{\circ} (V)$
$F_{2} + 2 e^{-} \to 2 F^{-}$	$2.87$
$A g^{2} + e^{-} \to A g^{+}$	$1.99$
$C o^{3 +} + e^{-} \to C o^{2 +}$	$1.82$
$H_{2} O_{2} + 2 H^{+} + 2 e^{-} \to 2 H_{2} O$	$1.78$
$M n O_{4}^{-} + 4 H^{+} + 3 e^{-} \to M n O_{2} + 2 H_{2} O$	$1.68$
$2 e^{-} + 2 H^{+} + I O_{4}^{-} \to I O_{3}^{-} + H_{2} O$	$1.60$
$M n O_{4}^{-} + 8 H^{+} + 5 e^{-} \to M n^{2 +} + 4 H_{2} O$	$1.51$
$A u^{3 +} + 3 e^{-} \to A u$	$1.50$
$C l_{2} + 2 e^{-} \to 2 C l^{-}$	$1.36$
$O_{2} + 4 H^{+} + 4 e^{-} \to 2 H_{2} O$	$1.23$
$M n O_{2} + 4 H^{+} + 2 e^{-} \to M n^{2 +} + 2 H_{2} O$	$1.21$
$B r_{2} + 2 e^{-} \to 2 B r^{-}$	$1.09$
$N O_{3}^{-} + 4 H^{+} + 3 e^{-} \to N O + 2 H_{2} O$	$0.96$
$C l O_{2} + e^{-} \to C l O_{2}$	$0.954$
$2 H g^{2 +} + 2 e^{-} \to H g_{2}^{2 +}$	$0.91$
$A g^{+} + e^{-} \to A g$	$0.80$
$H g_{2}^{2 +} + 2 e^{-} \to 2 H g$	$0.80$
$F e^{3 +} + e^{-} \to F e^{2 +}$	$0.77$
$O_{2} + 2 H^{+} + 2 e^{-} \to H_{2} O_{2}$	$0.68$
$M n O_{4}^{-} + e^{-} \to M n O_{4}^{2 -}$	$0.56$
$I_{2} + 2 e^{-} \to 2 I^{-}$	$0.54$
$C u^{+} + e^{-} \to C u$	$0.52$
$O_{2} + 2 H_{2} O + 4 e^{-} \to 4 O H^{-}$	$0.40$
$C u^{2 +} + 2 e^{-} \to C u$	$0.34$
$A g C l + e^{-} \to A g + C l^{-}$	$0.22$
$C u^{2 +} + e^{-} \to C u^{+}$	$0.16$
$2 H^{+} + 2 e^{-} \to H_{2}$	$0.00$
$F e^{3 +} + 3 e^{-} \to F e$	$- 0.036$
$P b^{2 +} + 2 e^{-} \to P b$	$- 0.13$
$N i^{2 +} + 2 e^{-} \to N i$	$- 0.23$
$C d^{2 +} + 2 e^{-} \to C d$	$- 0.40$
$F e^{2 +} + 2 e^{-} \to F e$	$- 0.44$
$C r^{3 +} + e^{-} \to C r^{2 +}$	$- 0.50$
$C r^{3 +} + 3 e^{-} \to C r$	$- 0.73$
$Z n^{2 +} + 2 e^{-} \to Z n$	$- 0.76$
$2 H_{2} O + 2 e^{-} \to H_{2} + 2 O H^{-}$	$- 0.83$
$M n^{2 +} + 2 e^{-} \to M n$	$- 1.18$
$A l^{3 +} + 3 e^{-} \to A l$	$- 1.66$
$H_{2} + 2 e^{-} \to 2 H^{-}$	$- 2.23$
$M g^{2 +} + 2 e^{-} \to M g$	$- 2.37$
$N a^{+} + e^{-} \to N a$	$- 2.71$
$C a^{2 +} + 2 e^{-} \to C a$	$- 2.76$
$B a^{2 +} + 2 e^{-} \to B a$	$- 2.90$
$K^{+} + e^{-} \to K$	$- 2.92$
$L i^{+} + e^{-} \to L i$	$- 3.05$

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Calculate the valency factor of the following: (i) Ca → Ca2++ 2e− (ii)K → K+ + e− (iii) Mn7+ + 5e−→ Mn2+

The correct option is C 2, 1, 5 To find the valency factor, we need to look at the change in oxidation state; of the atom under consideration. (i) Ca → Ca2++ 2e− 0 → +2 ⇒ v.f = 2 (ii) K→ K+ + e− 0 → +1 ⇒ v.f = 1 (iii) Mn7+ + 5e− → Mn2+ +7 → +2 ⇒ v.f = 5

Calculate the valency factor of the following:
(i) Ca $\to$ ${C a}^{2 +}$ + 2 $e^{-}$
(ii)K $\to$ $K^{+}$ + $e^{-}$
(iii) ${M n}^{7 +}$ + 5 $e^{-}$ $\to$ ${M n}^{2 +}$