Question

How long (in minutes) must a 5.40 A current be passed through an aqueous solution of zinc nitrate to deposit 87.5 g Zn?

A. 23,900 min
B. 797 min
C. 399 min
D. 2150 min

Answer 1

@aaronq

Answer 2

How many electrons does each zinc ion need to be reduced to it's elemental state?

Also, Ampere = Coulomb/sec

Answer 3

i'm not sure.

Answer 4

write the formula for zinc nitrate

Answer 5

Zn(NO3)2

Answer 6

what's the charge of the polyatomic ion \(\sf NO_3^x\)?

Answer 7

idk :(

Answer 8

it's -1, and there are two of them per formula unit.

This means that Zn is \(Zn^{2+}\).

Answer 9

ok so the answer has to be D right? if the charge is negative?

Answer 10

you're jumping all the steps. i have no idea what the answer is at this point, you have to use math to solve it, can't just guess

Answer 11

ok will you check my work when I post it?

Answer 12

yep! that would not be a problem

Answer 13

ok hold on..

Answer 14

87.5 g Zn X (1 mol Zn/65.38g Zn) X (1 mol e-/1 mol Zn) X (96485 C/1 mol e-)=129128.7473 C

129128.7473 C=5.4 A X seconds

129128.7473 C/5.4 A = seconds

seconds=23912.73098 X (1 minute/60 seconds)= 399 minutes

@aaronq

Answer 15

hmm you missed something, remember how for every Zn ion you need 2 electrons?

you had to multiply 129128.7473 C by 2 then proceed

Answer 16

good job though, otherwise

Answer 17

thanks! :)

Answer 18

no problem