Question

${{\text{P}}_{\text{4}}}{{\text{O}}_{{\text{10}}}}$ changes malonic acid into ${\text{C}}{{\text{O}}_2}$
A.True
B.False

Answer 1

To solve this question, we require knowledge about the reaction of ${{\text{P}}_{\text{4}}}{{\text{O}}_{{\text{10}}}}$ and malonic acid. ${{\text{P}}_{\text{4}}}{{\text{O}}_{{\text{10}}}}$ is also known as phosphorous pentoxide. It is a powerful desiccant and a dehydrating agent. It forms phosphoric acid with water. Malonic acid is a dicarboxylic acid, its ionised form is also known as malonate. It is an acid found in apples.

Complete step by step answer:
Phosphorous pentoxide reacts with carboxylic acids to form anhydrides. It is also used for the oxidation of alcohols. It is powerful enough to even convert mineral acids into their anhydrides. When ${{\text{P}}_{\text{4}}}{{\text{O}}_{{\text{10}}}}$ reacts with malonic acid, it forms an anhydride which is stable at $- {78.6^o}{\text{C}}$ . At room temperature, it polymerises to form highly colourful compound. The compound formed by the reaction of malonic acid in ${{\text{P}}_{\text{4}}}{{\text{O}}_{{\text{10}}}}$ is ${{\text{C}}_{\text{3}}}{{\text{O}}_{\text{2}}}$ which is also known as carbon suboxide. It forms a polymer with red, brown or yellow colour. As it is an anhydride of malonic acid, it is not related to carbon dioxide.
$\therefore$ The correct option is B, i.e. false.

Additional Notes: ${{\text{P}}_{\text{4}}}{{\text{O}}_{{\text{10}}}}$ is a white crystalline solid and is an anhydride of phosphoric acid. It is a dehydrating agent. It mostly exists as a dimer under normal condition. ${{\text{C}}_{\text{3}}}{{\text{O}}_{\text{2}}}$ is a member of allene group. It has three carbon atoms double bonded with each other and the terminal carbons double bonded with 1 atom each. It can be written as:
${\text{O = C = C = C = O}}$
It is a linear molecule with each of its carbon being sp hybridised. It is a colourless and odourless gas and its polymers are used as dyes for furs.

Note: Though ${{\text{C}}_{\text{3}}}{{\text{O}}_{\text{2}}}$ is named as tricarbon dioxide, we should we aware as to not get confused by the name as tricarbon dioxide and carbon dioxide are totally different compounds with different properties.