AP Chemistry

AP Chem Unit 3 Review

Multiple Choice

What holds molecules of CBr₄ together in a solid crystal of CBr₄?

• non polar covalent bonds

• polar covalent bonds

• intermolecular attractions from permanent dipoles

• intermolecular attractions from temporary dipoles

Multiple Choice

At room temperature and 1 atm, bromine (Br2) is a liquid and chlorine (Cl2) is a gas. Which of the following best explains that difference?

• London dispersion forces between molecules are stronger in bromine

• London dispersion forces between molecules are stronger in chlorine

• bromine has stronger covalent bonding

• chlorine has stronger covalent bonding

Multiple Choice

A solid is non-conductive, but conducts electricity when it is dissolved in water. What type of bonding is present in the solid?

• metallic

• ionic

• covalent

• London dispersion

Multiple Choice

Which of the following could be the chemical formula of a white, crystalline solid with the following properties (melting point = 1700°C, non conductive as solid, not soluble in water)?

• NaCl

• Al

• SiO₂

• C₁₂H₂₂O₁₁

Multiple Choice

Why are gases compressible?

• gas molecules are inert

• gas molecules have small masses

• gas molecules are far apart

• gas molecules move rapidly and randomly

Multiple Choice

Which of the following gases would have the highest density at STP conditions?

• H₂

• O₂

• N₂

• CO₂

Multiple Choice

A mixture of gases containing oxygen and nitrogen has a total pressure of 780mmHg. What is the mole fraction of oxygen if the partial pressure of oxygen is 260 mmHg?

• 0.50

• 0.33

• 260

• 3.0

Multiple Choice

Which of the following best describes how the distribution would shift if the temperature of the system were cooled?

• The peak would shift to the right and be lower.

• The peak would shift to the right and be higher.

• The peak would shift to the left and be lower.

• The peak would shift to the left and be higher.

Multiple Choice

Which gas would be expected to most deviate from ideal gas behavior?

• Helium, He

• Water vapor, H₂O

• nitrogen, N₂

• oxygen, O₂

Multiple Choice

A solution was prepared by dissolving 5.2g of CoCl₂

(molar mass 130.g/mol ) in enough water to make 200mL of solution. What is the molarity?

• 0.20 M

• 0.30 M

• 0.40 M

• 0.50 M

Multiple Choice

Which of the following is least soluble in water?

• Butane, C₄H₁₀

• Methanol, CH₃OH

• Glucose, C₆H₁₂O₆

• Formic Acid, HCOOH

Multiple Choice

Which of the following incorrectly matches the mixture to the optimal separation technique?

• Separating a mixture of dyes using chromatography

• Separating water and ethanol using distillation

• Separating a precipitate from water using filtration

• Separating a solution of salt and water using filtration

Multiple Choice

N₂ molecules absorb ultraviolet light but not visible light. I2 molecules absorb both visible and ultraviolet light. Which of the following statements explains the observations?

• More energy is required to make N₂ molecules vibrate than is required to make I₂ molecules vibrate.

• More energy is required to remove an electron from an I₂ molecule than is required to remove an electron from a N₂ molecule.

• Visible light does not produce transitions between electronic energy levels in the N₂ molecule but does produce transitions in the I₂ molecule.

• The molecular mass of I₂ is greater than the molecular mass of N₂.

Multiple Choice

When the metal surface is exposed to light photons of energy 3.3 x 10^-19 J/photon, electrons begin to be ejected from the metal. What is the frequency of these photons?

• 5 x 10¹⁴ Hz

• 5 x 10^-7 Hz

• 5 x 10⁵⁴ Hz

• 5 x 10^-19 Hz

Multiple Choice

The calibration curve was generated at a wavelength of 580 nm. What is the concentration of an unknown solution with an absorbance of 0.6?

• 5 µg/mL

• 10 µg/mL

• 15 µg/mL

• 20 µg/mL