19. Chemical Thermodynamics

Which of the following statements is/are true?

a) The rusting of iron by oxygen is a non-spontaneous reaction.

b) The addition of a catalyst to a reaction increases spontaneity.

c) The movement of heat from a cold object to a hot object is a non-spontaneous reaction.

d) The diffusion of perfume molecules from one side of a room to the other is a non-spontaneous reaction.

e) None of the above. 

Which of the following is (are) spontaneous processes?

(i) a ball rolling down a hill
(ii) a car rusting
(iii) the decomposition of water into H₂ gas and O₂ gas

A positive ΔS_system indicates what about the overall spontaneity of a process?

A process is always spontaneous under which conditions?

Which of the following is a true statement about the relationship between ΔG and K?

At what temperature does the following reaction become nonspontaneous?

2 NO (g) + O₂ (g) → 2 NO₂ (g)

Which of the following would have a negative ΔS?

Which of the following is a true statement about ΔS_surroundings?

Calculate ΔS_surr (in units of J/K) for the process in which 2.00 mol of water are placed into a freezer at −10.0℃.

Calculate ΔS°_rxn (J/K) for the formation reaction of the salt MgO (s).

The accompanying diagram shows how entropy varies with temperature for a substance that is a gas at the highest temperature shown. (c) If this substance is a perfect crystal at T = 0 K, what is the value of S at this temperature?

Which of the following processes are spontaneous and which are nonspontaneous: (d) lightning

Which of the following processes are spontaneous and which are nonspontaneous: (e) formation of CH4 and O2 molecules from CO2 and H2O at room temperature and 1 atm of pressure?

Which of the following processes are spontaneous and which are nonspontaneous: (a) the ripening of a banana

Indicate whether each statement is true or false. (a) A reaction that is spontaneous in one direction will be nonspontaneous in the reverse direction under the same reaction conditions. (b) All spontaneous processes are fast. (c) Most spontaneous processes are reversible. (d) An isothermal process is one in which the system loses no heat. (e) The maximum amount of work can be accomplished by an irreversible process rather than a reversible one.

Which of these processes is spontaneous? a. the combustion of natural gas b. the extraction of iron metal from iron ore c. a hot drink cooling to room temperature d. drawing heat energy from the ocean's surface to power a ship

Which of these processes are nonspontaneous? Are the nonspontaneous processes impossible? a. a bike going up a hill b. a meteor falling to Earth c. obtaining hydrogen gas from liquid water d. a ball rolling down a hill

Which of the following processes are spontaneous, and which are nonspontaneous? (a) Freezing of water at 2 °C (b) Corrosion of iron metal (c) Expansion of a gas to fill the available volume (d) Separation of an unsaturated aqueous solution of potassium chloride into solid KCl and liquid water

A standard air conditioner involves a refrigerant that is typically now a fluorinated hydrocarbon, such as CH2F2. An air-conditioner refrigerant has the property that it readily vaporizes at atmospheric pressure and is easily compressed to its liquid phase under increased pressure. The operation of an air conditioner can be thought of as a closed system made up of the refrigerant going through the two stages shown here (the air circulation is not shown in this diagram).

During expansion, the liquid refrigerant is released into an expansion chamber at low pressure, where it vaporizes. The vapor then undergoes compression at high pressure back to its liquid phase in a compression chamber. (e) Suppose that a house and its exterior are both initially at 31 °C. Some time after the air conditioner is turned on, the house is cooled to 24 °C. Is this process spontaneous or nonspontaneous?

A reaction that is spontaneous as written

Which of the following processes are spontaneous?