Multiple Choice
Which of the following is the correct method to calculate the percent ionization of HA in a 0.10 M solution, given that the acid dissociation constant (K_a) is known?
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6. Chemical Quantities & Aqueous Reactions
Calculate Oxidation Numbers
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In the reaction 16H^+ + 2Cr_2O_7^{2-} + C_2H_5OH → 4Cr^{3+} + 11H_2O + 2CO_2, which element is reduced?
A
Hydrogen
B
Oxygen
C
Carbon
D
Chromium
Verified step by step guidance1
Identify the oxidation states of the elements involved in the reaction before and after the reaction to determine which element is reduced.
Focus on chromium in the dichromate ion (Cr_2O_7^{2-}). In dichromate, chromium typically has an oxidation state of +6.
Look at the chromium in the product, Cr^{3+}, where chromium has an oxidation state of +3.
Since the oxidation state of chromium decreases from +6 to +3, chromium gains electrons and is therefore reduced.
Confirm that other elements (hydrogen, oxygen, carbon) do not show a decrease in oxidation state, so they are not reduced.
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