# I need help with the equations

1. Oct 4, 2008

### Emily266

A 20.0 gram piece of debris form a crash site was analyzed to determine the percent of nickel in the sample. The major components were chromium (III) and nickel (II). When the sample was oxidized with 50.0 ml of 6.0 M nitric acid, 3.0 grams of nickel (II) nitrate were formed.

a. write the two balanced equations. This is what I don't get
b. what was the mass of the nickel in the sample. I'm good on this part after I have the equation.

thank you

2. Oct 5, 2008

### Staff: Mentor

Don't feel alone, I don't get it too. At least in theory Cr can be oxidized to chromate, but I don't know if that'll happen. And as the question states that the sample contained Cr(III) and Ni(II) further oxidation wasn't necessary.

I suppose that it was meant to be "The major components were chromium and nickel".

Note, that even not having reaction equation you can still calculate percentage of nickel in the sample.

3. Oct 5, 2008

### Emily266

Thank you. I'm sorry but I don't quite see how to find the percent of Ni.

4. Oct 5, 2008

### Emily266

Would it be 3/20 X 100?

5. Oct 5, 2008

### Staff: Mentor

What is mass of nickel in 3 grams of nickel (II) nitrate?

6. Oct 5, 2008

### Emily266

0.96 g of Ni. Now do I do .96/20 X 100?

7. Oct 5, 2008

### Emily266

EPIPHANY!!! could these work as the equations??:

Cr + HNO3 -> Cr(NO3)3 + H2 and
Ni + HNO3 -> Ni(NO3)2 + H2

8. Oct 5, 2008

Could do.

9. Oct 5, 2008

woohoo!