Start with the skeleton half-reaction CrO₂^-→CrO₄^{2 -}. When balanced in basic solution, what other species appear on the right side of the equation, in addition to CrO₄^{2 -}?

Question

Quizplus · Accepted Answer

In order to balance the half-reaction in basic solution, we add OH- to both sides to neutralize the H+ ions, and then add water to balance the oxygen atoms. This gives us:

CrOS1U1B12S1U1B0S1U1P1 - S1S1P0 + 2 OH- -> CrOS1U1B14S1U1B0S1U1P12 - S1S1P0 + 3 H2OS1U1P1

We can see that we also have 3 electrons on both sides of the equation, but the question specifically asks for other species that appear on the right side besides the CrOS1U1B14S1U1B0S1U1P12 - S1S1P0 product. Looking at the right side of the equation, we can see that we have HS1U1B12S1U1B0O and electrons on the left side, but these have been consumed in the reaction to form H2OS1U1P1. Therefore, the only other species that appears on the right side is 2 HS1U1B12S1U1B0O, giving us answer choice A.

Start with the Skeleton Half-Reaction CrO2 - →CrO42 -

Start with the Skeleton Half-Reaction CrO₂^-→CrO₄^{2 -}