Question

1. For which system is ∆S<0?

	H2O(l)→H2O(g)
	H2O(g)→H2O(s)
	H2O(s)→H2O(l)
	H2O(s)→H2O(g)

2. Which pure substance under standard conditions would have the highest entropy?

	O2
	HCl
	CH3OH
	S

Answer 1

1. Entropy is basically degree of randomness of a system . So particles having lesser force of attraction will be more random and have more entropy.

Thus solid have least entropy then liquid and gas have maximum entropy amoung different state of matter.

So when H20(g)---> H20(s)

In this case only force of attraction is increasing and thus the randomness will be decreasing .

So here only ∆S < 0 .

2.  

At standard condtion sulphur is solid so have least entropy and O2 and HCl are gases but HCl being polar have dipole moment and more force of inter attraction between H and Cl and it also posses hydrogen bonding due to polar H so have less randomness and thus less entropy than O2 .

CH3OH is liquid at standarr condition so should have less entropy than oxygen but since it have six atoms in a single molecule and oxyen have only two atoms in a molecule.

Thus in 1 mole randomness of CH3OH is quite more than O2 because of being hexa-atomic .

So CH3OH(l) have more molar entropy at standard condition .

Hope u like the answer and please comment if any doubt .