Question

Write the half-reaction for ribose conversion to CO2. Is it an oxidation- or reduction- half reaction

Answer 1

Answer:

$5H_2O+C_5H_{10}O_5\rightarrow 5CO_2+20H^++20e^-$

Explanation:

Hello.

In this case, when ribose (C₅H₁₀O₅) yields carbon dioxide (CO₂) we write:

$C_5H_{10}O_5\rightarrow CO_2$

Which needs to be balanced by adding water and hydrogen ions:

$5H_2O+C_5H_{10}O_5\rightarrow 5CO_2+20H^++20e^-$

You can also see that there are 20 transferred electrons, since the carbon atoms in the ribose have 0 as their oxidation state and the carbon atoms in the carbon dioxide have +4 as the oxidation state, thus, each carbon transfers  4 electrons, a five carbon atoms transfer 20 electrons overall.

In such a way, since the carbon is increasing its oxidation state, such half reaction is an oxidation half reaction.

Best regards.