Final answer:
The decomposition of gas on a metal surface at high pressure is considered to be 0 order because the rate of the reaction does not depend on the concentration of the gas.
Step-by-step explanation:
In the decomposition of gas on a metal surface at high pressure, the reaction is considered to be 0 order because the rate of the reaction does not depend on the concentration of the gas.
This means that increasing the pressure of the gas does not affect the rate of decomposition. One example of a 0 order reaction is the decomposition of hydrogen peroxide to water and oxygen gas on a platinum surface. The reaction occurs at a constant rate regardless of the concentration of hydrogen peroxide.