91影视

A catalyst is a substance which can increase the rate of a reaction without being affected in the whole reaction process.

螖G掳= Free energy of activation or Gibes free energy

螖E_a = Activation energy.

螖厂^掳 = Entropy of activation

螖贬鈥� = enthalpy of the transition state - enthalpy of the reactants

螖S鈥� = entropy of the transition state - entropy of the reactants

螖G鈥� = free energy of the transition state - free energy of the reactants

k = rate constant.

K_eq = Equilibrium constant of a reaction.

螖贬^掳 = Enthalpy of activation

From the arrhenius equation, we can write,

Where k= rate constant.

A = Arrhenius constant.

E_a =activation energy.

R= Gas constant.

T= temperature.

If we introduce an catalyst, the reaction rate constant(k) will increase by decreasing the activation energy. So, in presence of catalyst, E_a decreases and k increases.

There are two others relations to compare the presence of catalyst and that are,

螖骋^鈥� = 螖贬^鈥� -T螖 S^鈥� 补苍诲鈥︹赌︹赌︹赌︹赌�1

螖贰_a = 螖贬^鈥� + RT. 鈥︹�︹�︹�︹�︹��..2

Where every terms has their own meanings.

Now, when, catalyst is applied, E_adeceases and as per equation 2, 螖H^鈥�also decreases as RT is a constant value.

Now, K_eq鈭�, Where k and k_-1 are rate constant in forward and backward direction respectively. If rate of a reaction increases which means formation of products (Forward reaction, K_eqalso increases, and from , becomes more negative or more spontaneous.

With decreasing , 螖S^鈥�increases to make the overall reaction negative.

The order of increase and decrease for 螖贬^掳螖G掳 and 螖厂^掳 becomes just same as for the transition state values of enthalpy, gibes free energy and entropy.