Find the rate law of the reaction 2 H + Ar → H 2 + Ar , which is elementary.

The reactions taking place in one step, without any intermediate, are called elementary reactions. In elementary reactions, reacting species simultaneously collide with each other, hence for elementary reactions, the reaction order equal to the stoichiometric coefficients for each reactant, i.e., the sum of stoichiometric coefficients of reactants, and it is always equal to the molecularity of the elementary reaction. Hence, the rate law of the reaction 2 H + Ar → H 2 + Ar R ∝ H 2 Ar R = K H 2 Ar

What are galvanic cells? Explain the working of a galvanic cell with a neat sketch taking Daniel cell as example.

Galvanic cell: A device which converts chemical energy into electrical energy by the use of spontaneous redox reactions is called Galvanic cell or voltaic cell. E.g: Daniel cell. Daniel cell: It is a special type of galvanic cell. It contains two half cells in the same vessel. The vessel is divided into two chambers. Left chambers is filled with ZnSO 4 ( aq ) solution and Zn-rod is dipped into it. Right chamber is filled with CuSO 4 ( aq ) solution and copper rod is dipped into it. Process diaphragm acts as a salt bridge. The two half cells are connected to external battery. Cell reactions: Ion Zn / ZnSO 4 half cell, oxidation reaction occurs Zn → Zn 2 + + 2 e - Ion Cu / CuSO 4 half cell, reduction reaction occurs. Cu 2 + + 2 e - → Cu The net cell reaction is Zn + Cu 2 + ⇔ Zn 2 + + Cu Cell is represented as Zn / Zn 2 + ∥ Cu 2 + / Cu

A reaction is second order with respect to a reactant. How is the rate of reaction affected if the concentration of the reactant is doubled?

Let the reaction be: A → products Let the concentration of the reactant A = x It is mentioned in the question that reaction is second order with respect to A reactant. So the rate r 1 = k A 2 = k x 2 If the concentration of reactant becomes double i.e. A = 2 x Then the rate of reaction would be r 2 = k 2 x 2 = 4 k x 2 = 4 r 1 Therefore the rate of reaction increases four times as concentration become double.