Question

Which compound is used to decrease the rate of decomposition of hydrogen peroxide ?

• A. HSO
• B. H₃PO₄
• C. HCI
• D. H₂CO,

Answer 1

Answer:

B. H₃PO₄

• The correct compound used to decrease the rate of decomposition of hydrogen peroxide is (B) H3​PO4​ (phosphoric acid).

• Hydrogen peroxide (H2​O2​) is an unstable compound that naturally decomposes into water (H2​O) and oxygen gas (O2​), as shown in the following reaction:

2H2​O2​→2H2​O+O2

​

• This decomposition is accelerated by factors such as light, heat, and the presence of certain catalysts (like metal ions). To slow down this process and increase the shelf life of hydrogen peroxide, stabilizers are added. Phosphoric acid (H3​PO4​) is a common stabilizer.

• How it works: Phosphoric acid acts as a chelating agent, meaning it can bind to and deactivate the trace metal ions (such as iron or copper) that may be present as impurities. These metal ions would otherwise act as catalysts, speeding up the decomposition reaction. By "locking up" these catalysts, the phosphoric acid effectively prevents them from accelerating the breakdown of hydrogen peroxide, thus stabilizing the solution.