Chemical principle 3

When heating a solution, the temperature in the solution is increased during a period of time. Which of the following statements is ture during this period?

• The solution is at boiling point.

• The solution is undergoing a phase change.

• The velocity of molecules in the solution is increasing.

• The solution’s temperature increase is proportional to its ΔHvaporization.

Which of the following equations represents a formation reaction?

• CO₂(g) + O₂(g) -> CO(g) + O₃(g)

• 1/8 S₈(s) + Cl₂(g) -> SCl₂(l)

• H₂(g) + Br₂(g) -> 2HBr(g)

• H₂(g) + 1/2 O₂(g) -> H₂O(g)

Additional gas is pumped inside a rigid container that stores compressed gas. Which of the following is a true statement about this system?

• Pressure is constant throughout the compression.

• There is no work done on the container.

• The molar concentration of gas is decreasing.

• The volume of the container is decreasing.

Which of the following pairs makes a correct comparison between the standard entropies of the following compounds at 25 ^oC?

• Br₂ > NO

• Ne > NH₃

• aqueous Mg²⁺ > aqueous Na⁺

• NaCl in solution < AgCl in solution

In a system undergoing adiabatic compression, what are the values of internal energy and heat if work done on the system is 500 J?

• Internal energy is 0 J and heat is -500 J.

• Internal energy is 0 J and heat is 500 J.

• Internal energy is 500 J and heat is 0 J.

• Internal energy is -500 J and heat is 0 J.

The entropy will usually increase when

a. a molecule is broken into two or more smaller molecules.

b. a reaction occurs that results in an increase in the number of moles of gas.

c. a solid changes to a liquid.

• a only

• b only

• c only

• All of a, b and c

Which one of the following thermodynamic quantities is not a state function?

• enthalpy

• entropy

• internal energy

• work

What is entropy?

• The disorder of a system.

• How cold a system is.

• Heat flow.

• The energy of a system.