AP Chem Review (MCQ 1)

Which of the following could be the identity of a white crystalline solid that exhibits the following properties?

• It melts at 320 ^oC

• It does not conduct electricity as a solid

• It conducts electricity in an aqueous solution.

• C6H12O6(s)

• NaOH(s)

• SiO2(s)

• Cu(s)

2 BaO₂(s) ↔ 2 BaO(s) + O₂(g)

ΔH° = 162 kJ/mol

A sealed rigid vessel contains BaO2(s) in equilibrium with BaO(s) and O₂(g) as represented by the equation above. Which of the following changes will increase the amount of BaO₂(s) in the vessel?

• Removing a small amount of O2(g)

• Removing a small amount of BaO(s)

• Adding He gas to the vessel

• Lowering the temperature

Tags

NGSS.HS-PS1-5

NGSS.HS-PS1-6

Which of the following best helps to explain why the value of ΔH° for the dissolving of CaF2 in water is positive?

• CaF2(s) is insoluble in water.

• CaF2(s) dissolves in water to form CaF2(aq) particles.

• Ca2+ ions have very strong ion-ion interactions with F- ions in the crystal lattice.

• Ca2+ ions have very strong ion-dipole interactions with water molecules in the solution.

Tags

NGSS.HS-PS1-4

NGSS.HS-PS3-1

Under which of the following conditions of temperature and pressure will H2 gas be expected to behave most like an ideal gas?

• 50 K and 0.10 atm

• 50 K and 5.0 atm

• 500 K and 0.10 atm

• 500 K and 50 atm

NO(g) + NO3(g) → 2 NO2(g) rate = k[NO][NO3] The reaction represented above occurs in a single step that involves the collision between a particle of NO and a particle of NO3. A scientist correctly calculates the rate of collisions between NO and NO3 that have sufficient energy to overcome the activation energy. The observed reaction rate is only a small fraction of the calculated collision rate. Which of the following best explains the discrepancy?

• The energy of collisions between two reactant particles is frequently absorbed by collision with a third particle.

• The two reactant particles must collide with a particular orientation in order to react.

• The activation energy for a reaction is dependent on the concentrations of the reactant particles.

• The activation energy for a reaction is dependent on the temperature.

Tags

NGSS.HS-PS1-5

Which of the following correctly identifies which has the higher first-ionization energy, Cl or Ar, and supplies the best justification?

• Cl, because of its higher electronegativity

• Cl, because of its higher electron affinity

• Ar, because of its completely filled valence shell

• Ar, because of its higher effective nuclear charge

Tags

NGSS.HS-PS1-2

NGSS.HS-PS1-1

• thermodynamically favorable, because K2 > 1

• thermodynamically favorable, because K3 > 1

• not thermodynamically favorable, because K1 < 1

• not thermodynamically favorable, because K3 < 1

The lattice energy of a salt is related to the energy required to separate the ions. For which of the following pairs of ions is the energy that is required to separate the ions largest? (Assume that the distance between the ions in each pair is equal to the sum of the ionic radii.)

• Na+(g) and Cl-(g)

• Cs+(g) and Br-(g)

• Mg2+(g) and O2-(g)

• Ca2+(g) and O2-(g)

Tags

NGSS.HS-PS1-3

NGSS.HS-PS2-4

A student prepared five solutions of CuSO4 with different concentrations, and then filled five cuvettes, each containing one of the solutions. The cuvettes were placed in a spectrophotometer set to the appropriate wavelength for maximum absorbance. The absorbance of each solution was measured and recorded. The student plotted absorbance versus concentration, as shown in the figure above. Which of the following is the most likely explanation for the variance of the data point for the 0.600 M CuSO4 solution?

• The cuvette into which the 0.600 M solution was placed had some water droplets inside.

• The cuvette into which the 0.600 M solution was placed was filled slightly more than the other cuvettes.

• The wavelength setting was accidentally moved away from that of maximum absorbance.

• The cuvette used for the 0.600 M solution had not been wiped clean before being put in the spectrophotometer.

If equal masses of the following compounds undergo complete combustion, which will yield the greatest mass of CO2?

• Benzene, C6H6

• Cyclohexane, C6H12

• Glucose, C6H12O6

• Methane, CH4