When glycerol (CH2OH-CHOH-CH2OH) is heated with potassium dichromate (K2Cr2O7), an exothermic reaction takes place. The potassium dichromate acts as an oxidizing agent, while glycerol undergoes oxidation. The reaction can be described by the following chemical equation:

2CH2OH-CHOH-CH2OH + K2Cr2O7 + H2SO4 → 3CO2 + Cr2(SO4)3 + K2SO4 + H2O

In this reaction, the glycerol molecules are oxidized to produce carbon dioxide (CO2) and water (H2O). Meanwhile, the potassium dichromate is reduced from the +6 oxidation state in Cr2O72- to the +3 oxidation state in Cr3+. The sulfuric acid (H2SO4) serves as a catalyst for the reaction.

The reaction is highly exothermic and releases a significant amount of heat. This is because the oxidation of glycerol is a highly favorable process, and the energy released from the reaction is in the form of heat. Additionally, the decomposition of potassium dichromate also contributes to the heat release.

Overall, the reaction between glycerol and potassium dichromate is a classic example of an oxidation-reduction reaction, where one species is oxidized (glycerol) while the other is reduced (potassium dichromate). The reaction produces carbon dioxide, water, chromium sulfate, and potassium sulfate, along with the release of a substantial amount of heat.