## 9.45

$\Delta S = \frac{q_{rev}}{T}$

Natalie LeRaybaud 1G
Posts: 54
Joined: Thu Jul 13, 2017 3:00 am

### 9.45

Can someone please explain how to go about doing this problem?

Use the information in Table 8.3 to calculate the changes in entropy of the surroundings and of the system for (a) the vaporization of 1.00 mol CH4(l) at its normal boiling point; (b) the melting of 1.00 mol C2H5OH(s) at its normal melting point; (c) the freezing of 1.00 mol C2H5OH(l) at its normal freezing point.

Brigitte Phung 1F
Posts: 50
Joined: Thu Jul 27, 2017 3:00 am
Been upvoted: 1 time

### Re: 9.45

For this problem, you will mainly be using the formulas, ΔS(surr) = - ΔH(system)/T and ΔS(system) = ΔH(system)/T. Note that the negative sign in the ΔS(surr) equation assumes that for exothermic reactions (ΔH of system is negative), the entropy of the surroundings is increased as it accepts heat released by the reaction. Table 8.3 gives you the Freezing Point, ΔHfus, Boiling Point, and ΔHvap for each of the substances, which you can use accordingly to what each subproblem asks (ex. use the respective substance's ΔHvap and the Boiling Point for its vaporization). For c) the ΔH(system) is negative because it is an exothermic reaction, whereas the other problems were endothermic reactions. Hope this helps!

Return to “Concepts & Calculations Using Second Law of Thermodynamics”

### Who is online

Users browsing this forum: No registered users and 1 guest