The quantity of antimony in an ore can be determined by an oxidation-reduction titration with an oxidizing agent. The ore is dissolved in hot, concentrated acid and passed over a reducing agent so that all the antimony is in the form Sb3 (aq). The Sb3 (aq) is completely oxidized by an aqueous solution of BrO3–(aq). Complete and balance the equation for this reaction in acidic solution.
The two half equations you need are
Sb^+3 ==> Sb^5+ + 2e
6e + BrO3^- + 6H^+==> Br^- + 3H2O
To determine the balanced equation for the oxidation-reduction reaction between Sb3+ and BrO3– in an acidic solution, you need to follow these steps:
Step 1: Identify the oxidation states of each element in the compounds involved in the reaction.
- In this case, Sb is present in the +3 oxidation state (Sb3+), and Br is present in the +5 oxidation state (BrO3–).
Step 2: Write the unbalanced equation for the reaction.
- Sb3+ (aq) + BrO3– (aq) →
Step 3: Balance the atoms that are neither oxygen nor hydrogen.
- Considering only the antimony atom (Sb), there is one Sb atom on the left side and one on the right side, so it is already balanced.
Step 4: Balance the oxygen atoms by adding water molecules (H2O).
- The BrO3– ion has three oxygen atoms, while the Sb3+ ion does not have any oxygen.
- Add three H2O molecules to the left side to balance the oxygen atoms.
Sb3+ (aq) + BrO3– (aq) → Sb3+ (aq) + 3H2O
Step 5: Balance the hydrogen atoms by adding H+ ions.
- The left side of the equation has no hydrogen atoms, while the right side has six.
- Add six H+ ions to the left side to balance the hydrogen atoms.
Sb3+ (aq) + BrO3– (aq) + 6H+ → Sb3+ (aq) + 3H2O
Step 6: Balance the charges by adding electrons (e–).
- The Sb3+ ion on the left side has a charge of +3, while the BrO3– ion and the H+ ion do not have any charges.
- Add six electrons (6e–) to the left side to balance the charges.
Sb3+ (aq) + BrO3– (aq) + 6H+ + 6e– → Sb3+ (aq) + 3H2O
Step 7: Verify that the equation is balanced by checking the number of atoms and charges on both sides.
- On the left side, there are one Sb atom, three O atoms, six H atoms, and no net charge.
- On the right side, there is still one Sb atom, six O atoms, six H atoms, and no net charge.
The final balanced equation for the reaction between Sb3+ and BrO3– in an acidic solution is:
Sb3+ (aq) + BrO3– (aq) + 6H+ + 6e– → Sb3+ (aq) + 3H2O