Anonymous
Anonymous asked in Science & MathematicsChemistry · 4 weeks ago

# Balance the following redox reaction equation, which takes place in a basic solution, using the half-reaction method?

Balance the following redox reaction equation, which takes place in a basic solution, using the half-reaction method?

NO3- (aq) + Al (s) --> NH3 (g) + Al(OH)4- (aq) [basic]

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• 4 weeks ago

First balance the reaction as if it is occurring in an acidic solution:

1. Divide the reaction into its two half-reactions:

NO3- --> NH3

Al --> Al(OH)4-

2. Balance O by adding H2O:

NO3- --> NH3 + 3 H2O

Al + 4 H2O --> Al(OH)4-

3. Balance H by adding H+:

NO3- + 9 H+ --> NH3 + 3 H2O

Al + 4 H2O --> Al(OH)4- + 4 H+

4. Balance charges by adding electrons:

NO3- + 9 H+ + 8 e- --> NH3 + 3 H2O

Al + 4 H2O --> Al(OH)4- + 4 H+ + 3 e-

5. Balance electrons by multiplying each equation by a number:

3 NO3- + 27 H+ + 24 e- --> 3 NH3 + 9 H2O

8 Al + 32 H2O --> 8 Al(OH)4- + 32 H+ + 24 e-

6. Add the two half-reactions and simplify:

3 NO3- + 8 Al + 23 H2O --> 3 NH3 + 8 Al(OH)4- + 5 H+

7. Make sure everything is balanced.

8 To convert to basic conditions, add as many OH- to both sides as you have H+. On the right side, the H+ and OH- will form 5 H2O. Simplify:

3 NO3- + 8 Al + 23 H2O + 5 OH- --> 3 NH3 + 8 Al(OH)4- + 5 H+ + 5 OH-

3 NO3- + 8 Al + 23 H2O + 5 OH- --> 3 NH3 + 8 Al(OH)4- + 5 H2O

3 NO3- + 8 Al + 18 H2O + 5 OH- --> 3 NH3 + 8 Al(OH)4-