Calculating Charge Magnitude for Nickel Coin Using Coulomb's Law

[tchounkovskii]

Homework Statement

A nickel coin has a mass of about 4.3g. Each mole (6.02e23 atoms) has a mass of about 58.2g

Homework Equations

I found the number of electrons on each coin, which is 1.245e24 and also the number of atoms on the coin which is 4.447e22.

The Attempt at a Solution

Now I have to find the magnitude of the charge of all of these electrons. I just started phys part two and need help. I Know that the C constant is, and I think I have to use the F=Q1Q2/r2but I can't come up with the solution

 

[LowlyPion]

Welcome to PF.

By C I think you mean the units of charge - Coulomb.

The formula you show is for the force between charges separated by a distance.

If you are looking for total charge in C, however, you will want to look up how many electrons makes up a Coulomb.

 

[tchounkovskii]

Well, I know that C=6.02 x 10^18 electrons, and I have 1.245 x 10^24 electrons, also the problem states that there are 28 electrons/atom on the nickel coin... would I multiply those?

 

[LowlyPion]

Well, I know that C=6.02 x 10^18 electrons, and I have 1.245 x 10^24 electrons, also the problem states that there are 28 electrons/atom on the nickel coin... would I multiply those?

You might want to use 6.24*10¹⁸ electrons/ Coulomb.
http://en.wikipedia.org/wiki/Coulomb

As to the 28 per atom, didn't you use that already to determine total electrons?

 

[tchounkovskii]

yes, that was to find the total electrons

 

[LowlyPion]

yes, that was to find the total electrons

So if you have total electrons and you know how many are in a Coulomb ...

 

[tchounkovskii]

I think i have to multiply but I'm not coming out with the right answer

 

[LowlyPion]

I think i have to multiply but I'm not coming out with the right answer

If I have 48 eggs, and there are 12 eggs in a dozen, and I wanted to know how many dozen I had, ... I wouldn't be multiplying.

 

[tchounkovskii]

Ok, cool...got it thanks