Question

Balance the following redox equation using the smallest integers possible and select the correct coefficient for the iron(II) hydroxide, Fe(OH)2.

Fe(OH)2(s) + CrO42-(aq) → Fe2O3(s) + Cr(OH)4-(aq) + H2O(l) + OH-(aq)

Answer 1

To balance the redox equation for Fe(OH) and CrO-, apply the half-reaction method appropriate for a basic solution, making sure to balance both the number of atoms and the electric charge. Determine the coefficient for Fe(OH)2 from the balanced half-reactions.

Step-by-step explanation:

Steps to Balance the Redox Equation

To balance the redox equation բₑ₍ₒₕ₎₂₍ₛ₎ ₊ Cᵣₒ₄₂₋₍ₐq₎ → բₑ₂ₒ₃₍ₛ₎ ₊ Cᵣ₍ₒₕ₎₄₋₍ₐq₎ ₊ ₕ₂ₒ₍ₗ₎ ₊ ₒₕ₋₍ₐq₎, we need to use the half-reaction method for balancing redox reactions in a basic solution. Based on the given information, the first step is to balance all elements except oxygen and hydrogen.

We see that iron is present as Fe2+ and Fe3+, and chromium transitions from Cᵣₒ₄₂₋ ₜₒ Cᵣ₃₊. ₜₕₑ բₑ₂₊ ₜₒ բₑ₃₊ to Fe transition is associated with the loss of one electron per iron atom.

The next step is to balance the oxygen by adding water molecules to the side deficient in oxygen and then balance hydrogen by adding hydroxide ions to the appropriate side.

Finally, we ensure that the number of electrons lost in the oxidation half-reaction equals the number gained in the reduction half-reaction. When combining the half-reactions, we should make sure that the number of electrons cancels out. After balancing the redox equation, the correct coefficient for iron(II) hydroxide, needs to be determined.

Based on the provided example equations, it's understood that the coefficients are adjusted to balance the overall equation while maintaining the charge and atom balance.

The correct coefficient for Fe(OH) can be derived from balancing the concerned half-reactions and ensuring that both mass and charge are balanced in the final equation.

Answer 2

To balance the redox equation, identify and balance the half-reactions. In basic solution, balance oxygen with water and hydrogen with hydroxide ions. The final step is balancing the charges with electrons and ensuring stoichiometric coefficients are correct. This is the correct coefficient for iron(II) hydroxide, Fe(OH)₂ is determined by the stoichiometry of iron in the reaction.

Step-by-step explanation:

To balance the given redox equation in basic solution, we need to balance both the atoms and the charges. The half-reaction method is an effective way to do this.

• Identify the oxidation and reduction half-reactions.
• Balance all elements except oxygen and hydrogen.
• Add water molecules to balance oxygen and hydroxide ions (OH-) to balance hydrogens.
• Balance the charges by adding electrons.
• Combine the half-reactions and balance the overall equation by ensuring that the electrons cancel out.

The provided equations suggest that in acidic solution, the balancing involves H₂O, H+, and electrons. In basic solution, OH- ions will be involved, as seen in the balanced half-reactions. The starting equation will undergo a transformation like the one given:

14OH- + 6Fe₂+ + Cr₂O₇₂- -> 6Fe₃+ + 2Cr₃+ + 7H₂O + 14OH-

After balancing, the correct coefficient for iron(II) hydroxide, Fe(OH)₂, is determined by the stoichiometry of iron in the reaction.