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In the half-reaction method, what is added to balance the charge of a half-reaction?
AWater molecules on the deficient side
BHydrogen ions on the deficient side
CHydroxide ions on the deficient side
DElectrons on the appropriate side
Answer & Solution
Correct answer: D. Electrons on the appropriate side
1. After oxygen and hydrogen are balanced, the two sides usually carry different total charges.
2. Electrons are added to whichever side makes the total charges equal.
3. For Fe2+ giving Fe3+, one electron on the right brings both sides to 2+.
4. Water balances oxygen atoms and hydrogen ions balance hydrogen atoms, so neither fixes charge.
5. Hydroxide ions enter only in the extra steps used for basic media.
_Source: OpenStax Chemistry (CC BY 4.0), Ch 4 "Stoichiometry of Chemical Reactions", section 4.2 Classifying Chemical Reactions_
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