Question 1

Which of the following best describes the general approach for determining the oxidation state of a carbon atom in an organic molecule?

Accepted Answer

Assign all bonds to carbon as if they were ionic, giving both electrons to the more electronegative atom in each bond.

Question 2

In the top compound (lactate), what is the oxidation state of the methyl carbon ($CH_3$) attached to the central carbon?

Accepted Answer

$-3$

Question 3

For the central carbon in the top compound (lactate), which is bonded to $CH_3$, $OH$, $H$, and $COO^-$, what is its oxidation state?

Accepted Answer

$0$

Question 4

What is the oxidation state of the carboxylate carbon ($COO^-$) in the top compound (lactate)?

Accepted Answer

$+3$

Question 5

In the middle compound (phosphoenolpyruvate), what is the oxidation state of the carbonyl carbon (the one double-bonded to oxygen)?

Accepted Answer

$+3$

Question 6

For the terminal carbon in the middle compound (phosphoenolpyruvate), which is bonded to $H$ and $CO$, what is its oxidation state?

Accepted Answer

$-1$

Question 7

In the bottom compound (3-phosphoglycerate), what is the oxidation state of the central carbon bonded to $OH$, $H$, $CH_3$, and $CO$?

Accepted Answer

$0$

Question 8

Which of the following statements is TRUE regarding the trend in oxidation states for the three carbons in the top compound (lactate)?

Accepted Answer

The oxidation state increases from the methyl carbon to the carboxylate carbon.

Question 9

If the central carbon in the top compound (lactate) is oxidized to a carbonyl group, what would be the change in its oxidation state?

Accepted Answer

It would increase from $0$ to $+2$.

Question 10

Which of the following best explains why the carboxylate carbon in all three compounds has a high oxidation state?

Accepted Answer

It is bonded to highly electronegative oxygen atoms, which withdraw electrons from the carbon.

Question 11

A mutation in a metabolic enzyme causes the conversion of the central carbon in the bottom compound (3-phosphoglycerate) from an alcohol to a ketone. What is the new oxidation state of this carbon?

Accepted Answer

$+2$

Question 12

Which of the following is the correct order of oxidation states for the three carbons in the bottom compound (3-phosphoglycerate), from the methyl group to the carboxylate group?

Accepted Answer

$-3$, $0$, $+3$

Question 13

Which of the following metabolic transformations involves an increase in the oxidation state of a carbon atom?

Accepted Answer

Conversion of an alcohol to a carboxylic acid.

Question 14

If a carbon atom is bonded to two hydrogens, one oxygen, and one carbon, what is its oxidation state?

Accepted Answer

$-1$

Question 15

Which of the following best describes the effect of phosphorylation (addition of $PO_3^{2-}$) on the oxidation state of the adjacent carbon in these compounds?

Accepted Answer

Phosphorylation does not directly change the oxidation state of the adjacent carbon.

Oxidation State Determination for Carbon Atoms in Biochemical Compounds

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