Two different gases occupy the two bulbs shown here. Consider the process that occurs when the stopcock is opened, assuming the gases behave ideally. (d) How does the process affect the entropy of the surroundings?

b. If energy can flow in and out of the system to maintain a constant temperature during the process, what can you say about the entropy change of the surroundings as a result of this process?

Predict the signs of ΔH and ΔS for this reaction. Explain your choice.

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?

Isomers are molecules that have the same chemical formula but different arrangements of atoms, as shown here for two isomers of pentane, C₅H₁₂.

(a) Do you expect a significant difference in the enthalpy of combustion of the two isomers? Explain.

Isomers are molecules that have the same chemical formula but different arrangements of atoms, as shown here for two isomers of pentane, C₅H₁₂.

(b) Which isomer do you expect to have the higher standard molar entropy? Explain.

The accompanying diagram shows how Δ𝐻 (red line) and 𝑇Δ𝑆 (blue line) change with temperature for a hypothetical reaction. Which of the following statements about this diagram is or are true?

b. The system is at equilibrium at 𝑇 = 300 K.

Consider a reaction A₂(𝑔) + B₂(𝑔) ⇌ 2 AB(𝑔), atoms of A shown in red in the diagram and atoms of B shown in blue. (a) If 𝐾_𝑐 = 1, which box represents the system at equilibrium?

Consider a reaction A₂(𝑔) + B₂(𝑔) ⇌ 2 AB(𝑔), atoms of A shown in red in the diagram and atoms of B shown in blue. (b) If 𝐾_𝑐 = 1, which box represents the system at 𝑄 < 𝐾_𝑐?

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

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?

a. the melting of ice cubes at −10 °C and 1 atm pressure

b. separating a mixture of N₂ and O₂ into two separate samples, one that is pure N₂ and one that is pure O₂

c. alignment of iron filings in a magnetic field

d. the reaction of hydrogen gas with oxygen gas to form water vapor at room temperature

e. the dissolution of HCl(g) in water to form concentrated hydrochloric acid

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.

(d) Does the amount of work that a system can do on its surroundings depend on the path of the process?

Consider the vaporization of liquid water to steam at a pressure of 1 atm. (a) Is this process endothermic or exothermic?

Consider the vaporization of liquid water to steam at a pressure of 1 atm. (b) In what temperature range is it a spontaneous process?

Consider the vaporization of liquid water to steam at a pressure of 1 atm. (c) In what temperature range is it a nonspontaneous process?

Consider the vaporization of liquid water to steam at a pressure of 1 atm. (d) At what temperature are the two phases in equilibrium?

The normal freezing point of n-octane (C₈H₁₈) is -57 °C. (b) In what temperature range is the freezing of n-octane a spontaneous process?

The normal freezing point of n-octane (C₈H₁₈) is -57 °C. (d) Is there any temperature at which liquid n-octane and solid n-octane are in equilibrium? Explain.

A system goes from state 1 to state 2 and back to state 1 following a reversible path in both directions. Which of the following statements about this process is or are true?

c. The value of w on going from state 1 to state 2 is equal in magnitude and opposite in sign to the value of w on going from state 2 back to state 1.

Indicate whether each statement is true or false. (a) ΔS is a state function. (b) If a system undergoes a reversible change, the entropy of the universe increases. (c) If a system undergoes a reversible process, the change in entropy of the system is exactly matched by an equal and opposite change in the entropy of the surroundings. (d) If a system undergoes a reversible process, the entropy change of the system must be zero.

The normal boiling point of Br₂(l) is 58.8 °C, and its molar enthalpy of vaporization is ΔHvap = 29.6 kJ/mol. (a) When Br₂(l) boils at its normal boiling point, does its entropy increase or decrease?

The normal boiling point of Br₂(𝑙) is 58.8  °C, and its molar enthalpy of vaporization is Δ𝐻_vap=29.6 kJ/mol. (b) Calculate the value of Δ𝑆 when 1.00 mol of Br2(𝑙) is vaporized at 58.8  °C.

The element gallium (Ga) freezes at 29.8 °C, and its molar enthalpy of fusion is ΔH_fus = 5.59 kJ/mol. (a) When molten gallium solidifies to Ga(s) at its normal melting point, is ΔS positive or negative?

The element gallium (Ga) freezes at 29.8 °C, and its molar enthalpy of fusion is ΔH_fus = 5.59 kJ/mol. (b) Calculate the value of ΔS when 60.0 g of Ga(l) solidifies at 29.8 °C.

Indicate whether each statement is true or false. (c) In a certain spontaneous process the system undergoes an entropy change of 4.2 J/K; therefore, the entropy change of the surroundings must be -4.2 J/K.

(a) Does the entropy of the surroundings increase for spontaneous processes?

(b) In a particular spontaneous process the entropy of the system decreases. What can you conclude about the sign and magnitude of ΔS_surr?