# Electrons in GRAMS

1. Sep 3, 2009

### deteam

Electrons in GRAMS :(

1. The problem statement, all variables and given/known data

Part1:

A sample of electrons is found to have a total charge of -7.68 x 10^8 C.
How many electrons are in this sample ?
===================================
Part 2 says:

What is the mass of the above sample of electrons in grams ?

2. Relevant equations
1 electron mass = 9.10938188 × 10^-28 grams]

3. The attempt at a solution

for part 1 My answer was 4.79e27. And its CORRECT

for part 2 i keep getting 4.36 as an answer but its wrong.

I used [1 electron mass = 9.10938188 × 10^-28 grams]

and multiplied that by my answer for part 1.

2. Sep 3, 2009

### diazona

Re: Electrons in GRAMS :(

How about keeping a couple more digits in that 4.79e27?

3. Sep 3, 2009

### deteam

Re: Electrons in GRAMS :(

tried that and got 4.366556698 and was still wrong even using only 3 sig figs

4. Sep 3, 2009

### PhaseShifter

Re: Electrons in GRAMS :(

5. Sep 3, 2009

### deteam

Re: Electrons in GRAMS :(

its a quiz online, tells me whether im correct or incorrect

Any more help guys ?

6. Sep 4, 2009

### PhaseShifter

Re: Electrons in GRAMS :(

Hmm, multiple choice or one of those annoying computer quizzes that counts an answer wrong when it's misspelled, has a space left out, etc?

The math looks OK to me, it could just be the quiz expects something like spelling out units rather than using the abbreviation.

7. Sep 4, 2009

### deteam

Re: Electrons in GRAMS :(

no its fill in the blank, but it specifically says "IN GRAMS" and "WITHOUT UNITS" and since the first part I got right with only 3 sig figs, I thought that was my problem here, but it was still wrong.

8. Sep 4, 2009

### Jay J

Re: Electrons in GRAMS :(

Sorry I got the same answer as you, must be something wrong with the quiz

Stay Up
-1-

9. Sep 4, 2009

### Staff: Mentor

Re: Electrons in GRAMS :(

I understand you have tried 4.37?

10. Sep 5, 2009

### deteam

Re: Electrons in GRAMS :(

ya I got the problem fixed it wasn't my answer that was wrong it was a technical error.

Thanks for the help guys !!