Energetics - True or False Types

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.

Chemical Energetics - Model Questions - Fill Blanks Type

1. The total energy of one mole of an ideal monatomic gas at 27°C is __________ calories. (JEE 1984)

Answer (3/2)RT = (1.5 mol)[1.987 cal/ (K mol.)](300 K) = 894.15 cal.

2. A system is said to be ___________ , if it can neither exchange matter nor energy with the surroundings. (JEE 1993)

Answer: isolated

3. The heat content of the products is more than that of the reactants in an _____________ reaction. (JEE 1993)

Answer: endothermic

4. When Fe (solid) is dissolved in acqueous hydrochloric acid in a closed vessel, the work done is _________________ . (JEE 1997)

Answer: zero

5. Enthalpy is an ____________ property. (JEE 1997)

Answer: extensive property.

It depends on mass of the substance