# Specific charge

1. Dec 2, 2009

### aurao2003

1. The problem statement, all variables and given/known data
a cu atom (mass number, 63;atomic number, 29) loses 2 electrons formed. for the ion formed calculate its specific charge in c\kg

2. Relevant equations
specific charge=charge\mass

3. The attempt at a solutionss
specific charge = (29x1.6x10-19)/(63x1.67x10-27)

i am obtaining 4.41x10^7 while the answer is 3.04x10^6.

thanks
ben

2. Dec 2, 2009

### rl.bhat

Net charge on the atom is + 2e.

3. Dec 2, 2009

### aurao2003

thanks for your propmt reply. that means my charge will be 3.2x10^-19. however, how do i calculate my mass?

cheers

4. Dec 2, 2009

### rl.bhat

Your mass in the solution is correct.

5. Dec 2, 2009

### aurao2003

thanks a lot.

regards
ben

6. Mar 20, 2010

### lillost

hey im new to this site so i really have no idea how this works but im trying to calculate specific charge as well.. but i still don't understand TT___TT...

7. Mar 21, 2010

### rl.bhat

Hi lillost, welcome to PF.
Specific charge means charge per unit mass, (e/
Two electrons are removed from the copper atom, So the net charge Q on it is 2*1.6*10^-19 C.
Mass of the copper atom is (63x1.67x10-27)kg.
Now fine the specific charge on copper.

8. Mar 21, 2010

### lillost

aww thank you!! ^___^
I'll kinda write down what im doing and then could you just tell me where i go wrong please?
so then 2 elctrons have the charge : 2(1.60x10-19)
Mass of 63Cu: 63(1.67x10-27)
and specific charge is: charge/mass
so we would have: 2(1.60x10-19)/63(1.67x10-27)
= 3.2x10-19/ 1.0521x10-25
= 3041535.976
= 3.04x10*6?
is that right?? im soo confused!! >____<

9. Mar 21, 2010