Q.Explain the effect of catalyst on reaction rate with an example.

Step 1. A catalyst is a substance that alters a reaction's rate without undergoing any permanent chemical change itself -- it may participate in an intermediate step, but is fully regenerated by the reaction's end.

Step 2. Mechanistically, a catalyst provides an ALTERNATIVE reaction pathway with a LOWER activation energy $E_a$ than the uncatalysed route. Since the fraction of sufficiently energetic collisions is $f=e^{-E_a/RT}$, even a modest reduction in $E_a$ dramatically increases the fraction of molecules able to react at a given temperature, raising the observed rate. …

Explain the activation-energy-lowering mechanism of catalysis, then support it with the book's $MnSO_4$/oxala …

• Claiming a catalyst changes the reaction's thermodynamics (e.g. $\Delta H$, or the identity/yield of products) -- it changes ONLY the rate/pathway, neve …