# Write the formula for a complex formed between Ni 2 and NH3, with a coordination

QuestionsCategory: ChemistryWrite the formula for a complex formed between Ni 2 and NH3, with a coordination
Lisa Howell asked 7 months ago
Write the formula for a complex formed between Ni 2+ and NH3, with a coordination number of 5.

Write the formula for a complex formed between Ni 2+ and CN–, with a coordination number of 4.

I am having trouble with these problem because I don’t really understand what coordination numbers are. I know that Ni is 2+ and I believe that NH3 is 1-, but I don’t understand how to make the coordination number 5.

Thank you so much.

Lisa Howell answered 7 months ago
Coordination number has slightly different meanings depending upon how it is used. One is in crystallography and the other is in complex formation. Here is a site that you can read about both.
http://en.wikipedia.org/wiki/Coordination_number

Basically, coordination number in complex ion formation is the number of atoms bound to the central atom. So if you want Ni^2+ and CN^- with coordination number of 4 you write [Ni(CN)4]^2- . The 2- charge is figures just like oxidation numbers; i.e., Ni ion is ^2+ and 4 CN ions at -1 each is -4. Then +2 + (-4) = -2.
You’re right that Ni^2+ is 2+ but NH3 is zero. All compounds are neutral; Ni is 2+ because that’s the charge on the ion.

Lisa Howell answered 7 months ago
Rearrange this equation to isolate a
b
(a+ c) (d-e)=f

Lisa Howell answered 7 months ago
What is the formula of the compound formed between the ions CO32- and Ni2+