Question

For each of the following reactions, predict the sign of ΔS°.

2Na(s) + Cl2(g) → 2NaCl(s)

KBr(s) → K+(aq) + Br−(aq)

2H2(g) + O2(g) → 2H2O(l)

C2H2(g) + 4F2(g) → 2CF4(g) + H2(g)

Answer 1

entropy of gas > entropy of aqueous > entropy of liquid > entropy of solid

1)

In reactant there is gas

So, reactant has more entropy than product.

So,

ΔS° is negative

2)

In product we have aqueous component and reactant is solid.

So, product has more entropy than reactant.

So,

ΔS° is positive

3)

In reactant there is gas

So, reactant has more entropy than product.

So,

ΔS° is negative

4)

In reactant there is more gas as compared to product

So, reactant has more entropy than product.

So,

ΔS° is negative