Name: Redox Reactions as a Basis for Titration
Uploaded: 2019-07-19
Duration: 7 min 17 s
Description: This video will help us learn about how redox indicators like potassium permanganate or diphenylamine are used to indicate the completion of a redox reaction...

Question

Balance the following equation in basic medium by both oxidation number and ion electron methods and identify the reductant and the oxidant:

Zn (s) + {NO}_{3}^{-} (aq) \to {Zn}^{2 +} (aq) + {NH}_{4}^{+} (aq)

Accepted Answer

Oxidation number method:
Step 1:
The net ionic equation is,
$Zn (s) + {NO}_{3}^{-} (aq) \to {Zn}^{2 +} (aq) + {NH}_{4}^{+} (aq)$
Step 2:
We assign oxidation numbers and balance the increase and decrease,
$4 Zn (s) + \overset{+ 5}{N} O_{3}^{-} (aq) \to 4 {Zn}^{2 +} (aq) + \overset{- 3}{N} H_{4}^{+} (aq)$

Step 3:
We balance charges by adding ${OH}^{-}$ , balance hydrogen by adding $H_{2} O$ ,
$4 Zn (s) + \overset{+ 5}{N} O_{3}^{-} (aq) + 7 H_{2} O (l) \to 4 {Zn}^{2 +} (aq) + \overset{- 3}{N} H_{4}^{+} (aq) + 10 {OH}^{-} (aq)$

Ion-Electron method:
Step 1:
We separate the ionic equation into oxidation and reduction half reactions:
$(O) : Zn (s) \to {Zn}^{2 +} (aq) (R) : {NO}_{3}^{-} (aq) \to {NH}_{4}^{+} (aq)$

Step 2:
Balance atoms other than oxygen and hydrogen, balance oxygen by adding water, balance hydrogen by adding
$H^{+}$ , add equal ${OH}^{-}$ on both sides, hydrogen and hydroxide ions combine with water and cancel out the extra water molecules,
$(R) : {NO}_{3}^{-} (aq) + 7 H_{2} O (l) \to {NH}_{4}^{+} (aq) + 10 {OH}^{-} (aq) (O) : Zn (s) \to {Zn}^{2 +} (aq)$

Step 3:
Balance the charges by adding electrons, manipulate both equations and eliminate them,
$(R) : {NO}_{3}^{-} (aq) + 7 H_{2} O (l) + 8 e^{-} \to {NH}_{4}^{+} (aq) + 10 {OH}^{-} (aq) (O) : (Zn (s) \to {Zn}^{2 +} (aq) + 2 e^{-}) \times 4__________________________________________________________{NO}_{3}^{-} (aq) + 4 Zn (s) + 7 H_{2} O (l) \to 4 {Zn}^{2 +} (aq) + {NH}_{4}^{+} (aq) + 10 {OH}^{-} (aq)$
It is clear that $Zn$ is getting oxidised, therefore, it is a reductant and ${NO}_{3}^{-}$ is getting reduced, therefore, it is an oxidant.

Balance the following equation in basic medium by both oxidation number and ion electron methods and identify the reductant and the oxidant:
$Zn (s) + {NO}_{3}^{-} (aq) \to {Zn}^{2 +} (aq) + {NH}_{4}^{+} (aq)$

Important Questions on Redox Reactions

Learn and Prepare for any exam you want !

Balance the following equation in basic medium by both oxidation number and ion electron methods and identify the reductant and the oxidant: Zns+NO3–aq→Zn2+aq+NH4+aq

Important Questions on Redox Reactions

Learn and Prepare for any exam you want !

Balance the following equation in basic medium by both oxidation number and ion electron methods and identify the reductant and the oxidant:
$Zn (s) + {NO}_{3}^{-} (aq) \to {Zn}^{2 +} (aq) + {NH}_{4}^{+} (aq)$