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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
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    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- 

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