# Write a mathematical formula for mole ratio. How long will it take to produce 2.415g of Ag metal from its salt solution by passing a current of 3A? Molar mass of Ag= 107.9 g mol-1 . - Chemistry

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Write a mathematical formula for mole ratio. How long will it take to produce 2.415g of Ag metal from its salt solution by passing a current of 3A? Molar mass of Ag= 107.9 g mol-1.

#### Solution

A mathematical formula for mole ratio:

Mole ratio = "Moles of product formed in half-reaction"/"Moles of electrons required in half-reaction"

Given: Mass of silver deposited (W) = 2.415 g, Current (I) = 3 A, Molar mass of silver = 107.9 g mol–1

To find: Time (t)

Formulae:

1. Mole ratio = "Moles of product formed in half-reaction"/"Moles of electrons required in half-reaction"
2. W = ("I" ("A") xx "t"("s"))/(96500 ("C"//"mole e"^-)) xx "mole ratio" xx "molar mass"

Calculation:

Stoichiometry: $\ce{Ag^+_{ (aq)} + e^- -> Ag_{(s)}}$

Using formula (1),

Mole ratio = (1  "mol")/(1  "mole e"^-)

Using formula (2),

W = ("I" ("A") xx "t"("s"))/(96500 ("C"//"mole e"^-)) xx "mole ratio" xx "molar mass of Ag"

2.415 cancel("g") = (3 "A" xx "t")/(96500 ("C"//cancel("mol")"e"^-)) xx (1 cancel("mol"))/(1 cancel ("mol") "e"^-) xx 107.9 "g"  cancel("mol"^-1)

t = (2.415 xx 96500 ("C" = cancel("A")"s"))/(3 cancel("A") xx 107.9) = 720 s = 12 min.

Time taken to produce 2.415 g of Ag at the cathode is 12 min.

Concept: Electrolytic Cell
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Chapter 5: Electrochemistry - Short answer questions (Type- II)

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SCERT Maharashtra Question Bank 12th Standard HSC Chemistry Maharashtra State Board
Chapter 5 Electrochemistry
Short answer questions (Type- II) | Q 8
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