Question

This is a Physical Chemistry Problem: What is the total change in entropy when 1.00 g of I₂ (s) at 300 K is heated isobarically to I₂ (g) at 500 K? This problem will require data from the appendix in the back of your textbook.

Answer 1

Solution :-

Lets first calculate the change in the entropy of the process using the standard entropy values

Delta S = Delta S product - Delta S reactant

            = I2(g) - I2(s)

            = 260.58 J per K mol - 116.14 J per K mol

            = 44.44 J per mol K

now using this value lets calculate the entropy change for the given temperatures

Delta S = Cp * ln (T2/T1)

Delta S = 44.44 J per mol K * ln(500K/300K)

Delta S = 22.7 J per mol K

This for the 1 mole I2

no lets calculate for the 1.0 g I2

1.0 g I2 * 22.7 J per mol K / 253.8 g = 0.097 J per mol K

So its 0.097 J per K