Multiple Choice
Which coefficient should be placed in front of O_2(g) to correctly balance the following chemical equation?O_2(g) + 2H_2O(l) + 4Ag(s) → 4OH^-(aq) + 4Ag^+(aq)
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3. Chemical Reactions
Balancing Chemical Equations
Multiple Choice
Which of the following is the correctly balanced chemical equation for the reaction: io3−(aq) + h2so3(aq) → i2(aq) + so42−(aq)?
A
io3−(aq) + 3 h2so3(aq) → i2(aq) + 3 so42−(aq) + 3 h2o(l)
B
io3−(aq) + h2so3(aq) → i2(aq) + so42−(aq) + h2o(l)
C
2 io3−(aq) + 5 h2so3(aq) → i2(aq) + 5 so42−(aq) + 5 h2o(l)
D
2 io3−(aq) + 5 h2so3(aq) → i2(aq) + 5 so42−(aq) + 6 h2o(l)
Verified step by step guidance1
Identify the oxidation states of iodine in the reactant ion \( \mathrm{IO_3^-} \) and in the product \( \mathrm{I_2} \) to determine the change in oxidation number, which will help in balancing the redox reaction.
Write the half-reactions for oxidation and reduction separately. For this reaction, \( \mathrm{IO_3^-} \) is reduced to \( \mathrm{I_2} \), and \( \mathrm{H_2SO_3} \) (sulfurous acid) is oxidized to \( \mathrm{SO_4^{2-}} \) (sulfate ion).
Balance each half-reaction for all elements except hydrogen and oxygen first, then balance oxygen atoms by adding \( \mathrm{H_2O} \) molecules, and balance hydrogen atoms by adding \( \mathrm{H^+} \) ions (if in acidic solution).
Balance the charges in each half-reaction by adding electrons \( (e^-) \) to the appropriate side, ensuring that the total charge is the same on both sides of each half-reaction.
Multiply the half-reactions by appropriate coefficients so that the number of electrons lost in oxidation equals the number gained in reduction, then add the half-reactions together, canceling out electrons and any other species that appear on both sides, to get the balanced overall equation.
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