True or False questions on Energetics/ Electrochemistry/ Chemical Kinetics

Energetics

1. First law of thermodynamics is not adequate in predicting the direction of a process.
(JEE 1982)

True

First law only says increase in internal energy of a system is due to heat transferred to the system and work done on the system. It does not predict the direction of a process.

Electrochemistry

1. The dependence of electrode potential for the electrode Mⁿ⁺ |M with conetration under STP conditions is given by the expression:


E = E° + 0.0591 V/n * log₁₀[Mⁿ⁺ |]

(JEE 1993)

False

The factor 0.0591 is applicable when the temperature is 298 K and not 273 K.

Chemical Kinetics

1. For a first order reaction, the rate of the reaction doubles as the concentration of the reactant(s) doubles. (1986)

Answer: True

Reason: For a first order reaction r = k[A].
Where r = rate of reaction
K = reaction constant
[A] = molar concentration of reactant
Hence if concentration doubles r also is doubled,.

2. Catalyst makes reaction more exothermic. (JEE 1987)

Ans: False
Catalyst does not affect the enthalpy of reaction. It affects only the rate of reaction.