Question

How do you balance `Ni + C_4H_8N_2O_2 -> Ni(C_4H_8N_2O_2)_2`?

Answer 1

`Ni + 2C_4H_8N_2O_2 -> Ni(C_4H_8N_2O_2)_2`

Explanation:

`Ni + C_4H_8N_2O_2 -> Ni(C_4H_8N_2O_2)_2`
as there are 1 molecule nickel, 4 molecules of carbon, 8 molecules of hydrogen, 2 molecules of nitrogen, and 2 molecules of oxygen in left hand side
but 1 molecule of nickel, 8 molecules of carbon, 16 molecules of hydrogen, 4 molecules of nitrogen, and 4 molecules of oxygen
so, by multiplying `C_4H_8N_2O_2` by `2` the equation will be balanced.

Answer 2

`"Ni"_text((aq])^(2+) + 2"C"_4"H"_8"N"_2"O"_text(2(aq]) -> "Ni"("C"_4"H"_7"N"_2"O"_2)_text(2(s]) darr + 2"H"_text((aq])^(+)`

Explanation:

The starting chemical equation given to you is actually incorrect.

This reaction takes place in aqueous solution and it involves the nickel(II) cation, `"Ni"^(2+)`, not nickel metal, `"Ni"`.

Reacting nickel(II) cations with dimethylglyoxime, `"C"_4"H"_8"N"_2"O"_2`, will produce an insolube solid called nickel dimethylglyoxime, `"Ni"("C"_4"H"_8"N"_2"O"_2)_2`, which will precipitate out of solution.

The nickel(II) cations can be delivered to the solution by a soluble salt like nickel(II) nitrate, `"Ni"("NO"_3)_2`.

The actual balanced chemical equation for this reaction can be written like this

`"Ni"_text((aq])^(2+) + 2"C"_4"H"_8"N"_2"O"_text(2(aq]) -> "Ni"("C"_4"H"_7"N"_2"O"_2)_text(2(s]) darr + 2"H"_text((aq])^(+)`

The reaction involves two dimethylglyoxime molecules acting as chelating agents to form the nickel dymethylglyoxime complex.

When the nickel(II) cations are delivered via nickel(II) nitrate, the reaction will produce

`"Ni"("NO"_3)_text(2(aq]) + 2"C"_4"H"_8"N"_2"O"_text(2(aq]) -> "Ni"("C"_4"H"_7"N"_2"O"_2)_text(2(s]) darr + 2"HNO"_text(3(aq])`

The nitrate anions, `"NO"_3^(-)`, are spectator ions in the reaction, meaning that they can be found on both sides of the chemical equation.

This reaction is used as a confirmation test for the presence of nickel(II) cations. Nickel dymethylglyoxime is a red precipitate.