Balancing equations for nickel and chromium oxidation with nitric acid

[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

 

[Borek]

a. write the two balanced equations. This is what I don't get

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.

 

[Emily266]

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

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

 

[Emily266]

Would it be 3/20 X 100?

 

[Borek]

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

 

[Emily266]

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

 

[Emily266]

EPIPHANY! could these work as the equations??:

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

 

[Borek]

Could do.

 

[Emily266]

woohoo!