Chem10

Question 1

State Faraday’s First Law

Answer 1

Mass of substance deposited is proportional to quantity of electricity passed (m ∝ Q)

Question 2

What is the mathematical form of Faraday’s First Law?

Answer 2

m = (M × I × t)/(z × 96500) where z = charge on ion

Question 3

If 2A for 1h deposits 2.4g Mg, find equivalent mass (z=2)

Answer 3

Q=2×3600=7200C; Eq.mass=(2.4×96500)/7200=32.17g (close to Mg²⁺ theoretical 12.15g)

Question 4

How much Cu is deposited by 10A for 30 min? (Cu=63.5)

Answer 4

Q=10×1800=18000C; m=(18000×31.75)/96500=5.93g

Question 5

Why is mass directly proportional to current?

Answer 5

Because m ∝ Q and Q = I × t

Question 6

If time doubles while current stays constant, what happens to mass?

Answer 6

Mass doubles (m ∝ t)

Question 7

What is the relationship between 1 coulomb and silver?

Answer 7

1C deposits 1.118 mg of Ag

Question 8

Derive how 96,500C became 1 Faraday

Answer 8

To deposit 108g Ag (1 eq.mass): Q=108g/0.001118g/C≈96,500C

Question 9

If 1.5A deposits 0.5g metal in 1h, find equivalent mass

Answer 9

Q=1.5×3600=5400C; Eq.mass=(0.5×96500)/5400=8.94g

Question 10

Why is Faraday’s First Law important industrially?

Answer 10

Predicts exact amount of product from given current/time

Question 11

How does charge relate to moles of electrons?

Answer 11

1 mole e⁻ = 1 Faraday = 96,500C

Question 12

What is the industrial significance of aluminum’s 3+ charge?

Answer 12

Needs 3× more electricity per mole than 1+ ions (3 Faradays/mole)