Question

The standard molar entropy for Br2(g) is 245.46 J/(mol·K) at 25°C. Given that ΔS° = 104.58 J/K for the dissociation of one mole of Br2(g) into Br(g) at 25°C, find the standard molar entropy for Br(g) at 25°C. Enter your answer with two decimal places and no units.

Answer 1

The standard molar entropy for Br(g) at 25°C is 175.02J/K mol.

Step-by-step explanation:

`Br_2(g)\rightarrow 2Br(g),\Delta S^o=104.58 J/K`

`\Delta S^(o)_(m,Br_2)=245.46 J/(mol/K)`

`\Delta S^o=2 mol* \Delta S^(o)_(m,Br) - 1 mol*\Delta S^(o)_(m,Br_2)`

`\Delta S^o= \sum \Delta S^(o)_(Products)-\sum \Delta S^(o)_(reactants)`

`104.58 J/K=2 mol* \Delta S^(o)_(m,Br) -1 mol* 245.46 J/(mol/K)`

`2 mol* \Delta S^(o)_(m,Br)=350.04J/K`

`\Delta S^(o)_(m,Br)=175.02J/K mol`

The standard molar entropy for Br(g) at 25°C is 175.02J/K mol.