Question

If 20.6 g of gold is deposited on the negative electrode of an electrolytic cell in a period of 2.61 hours, then what is the current through the cell during this period? (Assume that the gold ions carry one elementary unit of positive charge and the atomic mass of gold is 197.0 g/mol.)

Answer 1

Remember that the conversion for coulombs to moles is \(F\approx 96500\). I would recommend making use of Dimensional Analysis for this problem.

Answer 2

So I took 197 and divided it by 6.02E23 and got 3.27E24

Answer 3

then 20.6/3.27E24 and got 6.299E24

Answer 4

that times 1.602E-19 divided by 9396 and got 107.4A? but it says its wrong

Answer 5

Yeah, I'm not sure why you're dividing the mass by \(N_A\), though (your first step).

Answer 6

I did that to find the mass of a single gold atom, I dont have to do that?

Answer 7

Good thinking, but that's not quite required. I also believe you're dropping a negative exponent somewhere above.

Answer 8

Could you explain that I little more? so I just do 20.8 divide by 197?

Answer 9

That is correct.

Answer 10

I'll add a little bit more, to make it more clear:

Answer 11

We know the molecular mass and we know the mass of how many atoms were transferred. The number of atoms equals the number of electrons, and the conversion factor between moles and coulombs is 96,500. We know that current is charge per unit time (that is coulombs/seconds).

We can put all of that together to find our answer. If you need any further help, please ask away.

Answer 12

so 20.6/197 is .1046
Then that times 1.602E-19 divided by 9396 is 1.78E-24
But it says that is wrong

Answer 13

I don't quite get why you're multiplying by 1.602E-19?

Answer 14

I don't understand so 20.6/197 take that and divide by 9396? Thats 1.11E-5 and it says thats wrong

Answer 15

So, remember that 20.6/197 gives you the number of moles, not coulombs. To convert from moles to coulombs we multiply by 96500.

Answer 16

Oh my gosh thank you!

Answer 17

Yep, sure thing.