# Help calculating charge of Cl- and K+ ions

1. Jun 3, 2006

### runran

Sorry if this is a ridiculously simple problem, but I don't get it. The professor didn't give examples of how to do this and it's been years since I've taken science courses. I have to determine the electric force (Coulomb's Law) on the K+ ion due to the Cl- ion 9E-10m away. How do you determine the charge of the K+ and Cl- ions? K(19) has atomic mass 39.0983 and Cl(17) has atomic mass 35.4527... but I don't know where to start with calculations. Please help? Thank you.

2. Jun 3, 2006

### Hootenanny

Staff Emeritus
K+ indicates a charge of +1e; Cl- indicates a charge of -1e, where e is the charge of an electron in coulombs. Therefore, the charge on the K+ in coulombs is 1 $\times$ (1.6x10-19). Do you follow?

~H

3. Jun 3, 2006

### runran

O.

I guess I was making it harder than it needed to be. Sorry, that was stupid now. Thank you : )

4. Jun 3, 2006

### Hootenanny

Staff Emeritus
No problem

~H