balance these redox reactants & determine oxidator agent and reducing agent
A. Zn + NO3- --> Zn+2 +NH4 + Acid
B. Cr(OH)3 + H2O2 --> CrO4 -2 + H20 (Basic)
To balance a redox reaction, you need to follow these steps:
Step 1: Assign oxidation numbers to all the elements in the reaction.
Step 2: Identify the elements that are undergoing oxidation and reduction.
Step 3: Write separate half-reactions for oxidation and reduction.
Step 4: Balance the number of atoms on both sides of each half-reaction by adding the appropriate coefficients.
Step 5: Balance the charges on both sides of each half-reaction by adding electrons.
Step 6: Multiply each half-reaction by an appropriate factor so that the number of electrons canceled out in the full reaction.
Step 7: Add the balanced half-reactions together to get the balanced overall reaction.
Let's apply these steps to the given reactions:
A. Zn + NO3- -> Zn+2 + NH4+ (Acidic)
Step 1: Assign oxidation numbers:
Zn: 0
NO3-: -1 for each oxygen, so N has an oxidation number of +5
Zn+2: +2
NH4+: +1 for H, so N has an oxidation number of -3
Step 2: Identify oxidation and reduction:
Zn is being oxidized from 0 to +2, and NO3- is being reduced from +5 to -3.
Step 3: Write half-reactions:
Oxidation: Zn -> Zn+2
Reduction: NO3- -> NH4+
Step 4: Balance the number of atoms:
Oxidation: Zn -> Zn+2 (balanced)
Reduction: 2NO3- -> NH4+ (not balanced)
Step 5: Balance the charges:
Oxidation: Zn -> Zn+2 (balanced)
Reduction: 2NO3- + 12H+ -> NH4+ (balanced)
Step 6: Multiply each half-reaction by an appropriate factor to cancel out electrons:
Oxidation: Zn -> Zn+2 (balanced)
Reduction: 6NO3- + 24H+ -> 6NH4+ (balanced)
Step 7: Add the balanced half-reactions:
Zn + 6NO3- + 24H+ -> Zn+2 + 6NH4+ (balanced)
In this reaction, Zn is the reducing agent because it is undergoing oxidation, and NO3- is the oxidizing agent because it is undergoing reduction.
B. Cr(OH)3 + H2O2 -> CrO4-2 + H2O (Basic)
Follow the same steps as described above to balance the reaction and determine the oxidizing agent and reducing agent. The final balanced equation will be:
Cr(OH)3 + 4H2O2 -> CrO4-2 + 5H2O
In this reaction, H2O2 is the reducing agent because it is undergoing oxidation, and Cr(OH)3 is the oxidizing agent because it is undergoing reduction.