Balance Reaction Using Oxidation States Method

[romihan95]

I need help balancing this reaction on my chemistry homework, please!

Must be done using oxidation states method

NO₃^- + Zn +OH^- + H₂O = Zn(OH)₄^2- + NH₃

[ChenBeier]

In alkaline envirement oxidation by adding of OH- on educt side and water on product side, if oxygen is involved ,by reduction vise versa.

Look for redox pairs

Redox pair NO₃- / NH₃ and Zn/ [Zn( OH)₄]₂-

NO₃- + 6 H₂O => NH₃ + 9 OH- add water and OH-

Zn + 4 OH- => [Zn(OH)₄]₂- only add OH- no oxygen transfer.

Balance charges by using electrons

NO₃- + 6 H₂O + 8 e- => NH₃ + 9 OH- Reduction

Zn + 4 OH- => [Zn(OH)₄]₂- + 2 e- Oxidation

kgV of electron is 8

Multiplication of second equation by 4

4 Zn + 16 OH- => 4 Zn(OH)₄]₂- + 8 e-

Addition

4 Zn + NO₃- + 6 H₂O + 7 OH- => 4 [Zn(OH)₄]₂- + NH₃