Question

For which of the following processes, $\Delta S$ is negative?

• A. $N_2(g,273K)\to N_2(g,300K)$
• B. $N_2(g,1atm)\to N_2(g,5atm)$
• C. $C\left(diamond\right)\to C\left(graphite\right)$
• D. $H_2\left(g\right)\to 2H\left(g\right)$

Answer 1

The correct option is B $N_2(g,1atm)\to N_2(g,5atm)$

(A)When we increase the temperature of a gas then randomness is increased due to kinetic energy gained by molecules.

So, $\Delta$$S>0$

(B)When pressure increases then molecules of gas will come closer and intermolecular distance decreases so entropy will also decrease.

and $\Delta$$S<0$

(C)When Diamond is converted into graphite when it is heated to ${1500}^{o}C$ and entropy is increased so $\Delta$$S>0$

(D)$H_2$ molecule is converted into atoms, So entropy will increase.

So $\Delta$$S>0$