1. Consider a process involving 1 mole of an ideal gas that takes place by the following pathway, at a constant temperature of 25oC: P1 = 2.5 atm → P2 = 0.25 atm → P3 = 2.5 atm
Both steps occur irreversibly.
Calculate w, q, ΔE and ΔS for this process.
2. For methanol, ΔHvap = 39.2 kJ/mol at its boiling point, 65 oC. Calculate the values for ΔS, q, w, and ΔE for the vaporization of methanol at 65 oC and 1 atmosphere pressure.
3. Only one answer per part can be true (endothermic, exergonic, T dependence). You need to answer all of the questions. If you get the answers right, you will receive credit.
The spontaneity of a standard reaction, ΔGo, depends on both ΔHo and ΔSo. Assume that ΔHo and ΔSo are independent of Temperature.
H2 (g) + Br2 (l) → 2 HBr (g)
ΔHorxn -72.8 kJ
ΔSorxn 114 J/K
Given the following reaction and data table, decide if each of the statements shown below are True or False.
This reaction is endothermic
This reaction is exothermic
This reaction is endergonic (ΔGo > 0) at 298 K
This reaction is exergonic (ΔGo < 0) at 298 K
This standard reaction will only be spontaneous at high temperatures (T > 638 K)
This standard reaction will only be spontaneous at low temperatures (T < 638 K)
This standard reaction will be spontaneous at all temperatures
This standard reaction will not be spontaneous at any temperature
4. What are the changes in free energy, enthalpy and entropy and the sign of work for the following process carried out at 100.8o C. The boiling point of HCOOH is 100.8o C.
HCOOH (g) → HCOOH (l)
(+,-,0)
ΔHo
ΔGo
ΔSo
w
5. Order the follow processes from (1) the least work done by the system to (5) the most work done by one mole of an ideal gas at 25oC.
An isothermal expansion from 1 L to 100 L at an external pressure of 0.25 atm.
An isothermal expansion from 2 L to 8 L at an external pressure of 3.3 atm.
A free isothermal expansion from 1 L to 100 L.
A reversible isothermal expansion from 0.25 L to 12.5 L.
A reversible isothermal expansion from 1 L to 100 L.