AP Chem Winter Exam Review

Describe what happens to the average speed of the Xe atoms in the container in diagram 3 as the original volume V is reduced to V/2 at a constant temperature. Explain.

The average speed stays the same, and the temperature is constant.

In terms of atomic structure, explain why the first-ionization energy K is less than that of Ca.

The first ionization energy of K is less than that of Ca because the electron removed from K is less strongly attracted to (and more easily removed from) the K nucleus, which has fewer protons than Ca.

The crystal structure of NaBr is represented in the diagram above. Which statement correctly compares crystalline NaBr (s) to molten NaBr (l) in terms of electrical conductivity?

Crystalline NaBr contains no freely moving electrons to conduct electricity, but molten NaBr is composed of freely moving Na+ and Br- ions, which allow it to be a good conductor of electricity.

A student obtains a 10.0g sample of a white powder labeled as BaCl2. After completely dissolving the powder in 50.0mL of distilled water, the student adds excess Na2SO4 (s), which causes a precipitate of BaSO4 (s) to form, as represented by the equation Ba 2+ (aq) + SO4 2- (aq) -> BaSO4 (s). The student filters the BaSO4 (s), rinses it, and dries it until it's mass is constant. Which of the following scientific questions could best be answered based on the results of the experiment?

Is the BaCl2 (s) used in the experiment pure?

The diagram above represents four cations, all shown to the same scale. Which cation would be predicted by Coulomb's law to have the strongest ion-dipole attraction to water, and why?

Mg 2+, because it has the largest charge-to-size ratio.

The infrared spectrum above represents the absorption of certain wavelengths of radiation by molecules of CO2. Which of the following best explains what occurs at the molecular level as the CO2 molecules absorb photons of the infrared radiation?

The atoms in the CO2 molecules increase their vibration as the bonds between the atoms bend and stretch.

A solid compound of a group 1 (alkali) metal and a group 17 (halogen) element dissolves in water. The diagram above represents one type of solute particle present in the solution. Which of the following identifies the solute particle and best helps explain how the solute particle interacts with water molecules?

The particle is a positive ion, and the interactions are ion-dipole attractions.

Describe how to use the information from the mass spectrum to determine the average atomic mass of the element.

The weighted average is calculated by finding the sum of three terms, each of which is the product of the proportional abundance of each isotope and the mass of each isotope. (0.79)(24) + (0.10)(25) + (0.11)(26)

Ions in a certain volume of 0.20 M NaCl (aq) are represented in the box above on the left. In the box above on the right, draw a particle diagram that represents the ions in the same volume of 0.10 M CaCl2 (aq).

There are four unshaded circles that represent Ca2+ ions and eight shaded circles that represent Cl- ions.

On the graph, which shows the potential energy curve of two N atoms, carefully sketch a curve that correspond to the potential energy of two O atoms versus the distance between their nuclei.

Up and to the left more