AP Chemistry Fall Final Review

a. He will escape faster because the He atoms are moving at a higher average speed than the Ne atoms.

A 0.5 mol sample of He and a 0.5 mole sample of Ne are placed separately into 10.0 L rigid containers at 25° C. Each container has a pinhole opening. Which of the gases, He or Ne, will escape faster through the pinhole and why?

c. about 0.20 atm because H2 comprises 20% of the total number of moles of gas.

A gas mixture at 0° C and 0.10 mol of H2 0.015 mol of O2 and 0.025 mol of N2. Assuming ideal behavior, what is the partial pressure of hydrogen gas in the mixture

b. C3H6O

A sample of a compound known to consist of only carbon, hydrogen, and oxygen is found to have a total mass of 29.05 g. If the mass of carbon is 18.02 g, and the mass of hydrogen is 3.03 g, what is the empirical formula of the compound?

d. 2.25 atm, because doubling the number of moles of Ar doubles it's partial pressure

An equimolar mixture of N2 and Ar is kept inside a rigid container at a constant temperature of 300 K. The initial partial pressure of Ar in the mixture is 0.75 atm. An additional amount of Ar was added to the container, enough to double the number of moles of gas in the mixture. Assuming ideal behavior, what is the final pressure of the gas mixture after the addition of the Ar gas?

e. Mg3X2

Atoms of an element, X, have the electronic configuration shown above. The compound most likely formed with magnesium, Mg, is:

d. unlike BF3, NF3 has a nonplanar geometry due to an unshared pair of electrons on the N atom.

The BF3 molecule is nonpolar, whereas the NF3 molecule is polar. Which of the following statements accounts for the difference in polarity of the two molecules?

c. 120

The F-B-F bond angle in the BF3 molecule is

a. The average mass of a single carbon atom, measured in amus.

The average mass, in grams, of one mole of carbon atoms is equal to

b. 1s2 2s2 2p6 3s2 3p3

The complete photoelectron spectrum of an element is given above. Which of the following electron configurations is consistent with the spectrum?

c. CBr4

The compound CCl4 is nonflammable, and was once commonly used in fire extinguishers. On the basis of the periodic properties, which of the following compounds can most likely be used as a fire-resistant chemical?

b. greatest in container B

The density of the gas, in g/L, is

c. 5.0 x 10^14 s^-1

The diagram above represents the photoelectric effect for a metal. When the metal surface is exposed to light with increasing frequency and energy of photons, electrons first begin to be ejected from the metal when the energy of the photons is 3.3 x 10^-19 J. which of the following is closest to the frequency of the light with photon energy of 3.3 x 10^-19 J

a. dotted line higher on left

The distribution of speeds of H2 molecules at 273K and 1 atm is shown in the diagram above. Which of the following best shows the speed distribution of He atoms under the same conditions of temperature and pressure?

b. B, because it has three valence electrons

The first five ionization energies of a second-period element are listed in the table above. Which of the following correctly identifies the element and best explains the data in the table?

c. X3P2

The ionization energies of an unknown element, X, are listed in the table below. Which of the following is the most likely empirical formula of a compound formed from element X, and phosphorus, P?

a. The attractive and repulsive forces are balanced, so the atoms will maintain an average internuclear distance B.

The potential energy of a system of two atoms as a function of their internuclear distance is shown in the diagram above. which of the following is true regarding the forces between the atoms when their internuclear distance is B

b. Oxidation Half-reaction: Cu—>Cu^2+ + 2e- Reduction Half-reaction: Ag+ + e- —> Ag

The reaction between solid copper and aqueous silver nitrate produces solid silver and a blue solution, as represented by the balanced equation shown above. Based on the balanced equation, which of the following identifies the oxidation and reduction, half-reactions?

d. Increasing number of unshared pairs of electrons.

according to the VSEPR model, the progressive decrease in the bond angles in the series of molecules CH4, NH3, and H2O is best accounted for by the:

b. MgO

according to the information in the table below, a 1.00 g sample of which of the following contains the greatest mass of oxygen?

c. it has a weaker attraction for the stationary phase that it has for the mobile phase.

based on the results of the paper chromatography experiment shown above, which of the following can be concluded about the dye

b. Equation B

choose the equation that represents a precipitation reaction:

a. S

consider atoms of the following elements. Assume that the atoms are in the ground state. Choose the atom that contains exactly two unpaired electrons.

c. Ga

consider atoms of the following elements. Assume that the atoms are in the ground state. The atom that contains only one electron in the highest occupied energy sub level is:

d. FeS is the limiting reactant and 0.5 mol of O2 remains unreacted

due to the presence of FeS as an impurity, the combustion of some types of coal results in the formation of SO2, as represented by the equation above. Which of the following statements is correct when 2.0 mol of FeS reacts with 4.0 mol of O2?

a. PHe < PNe < PAr

equal numbers of moles of He, Arc and Ne are placed in a glass vessel at room temperature. If the vessel has a pinhole sized leak, which of the following will be true regarding the relative values of the partial pressures of the gases remaining in the vessel after some of the gas mixture has effused?

d. H2O and Cl-

for the dissolution of HCl in water represented above, which of the following pairs includes the Bronsted-Lowry bases (meaning the base and the conjugate base)?

c. 4 x 6.02 x 10^23 potassium atoms

in 1.00 mol of potassium zirconium sulfate trihydrate, K4Zr(SO4)4 • 3H2O, there are

d. Nonmetals have higher ionization energies because they are closer to having filled a complete energy level.

in general, do metals or nonmetals from the same period have higher ionization energies? Why?

b. Z : X : Z (X has eight electrons around it)

in the following diagrams, elements are represented by X and Z, which form molecular compounds with one another. Which diagram represents a molecule that has a bent molecular geometry?

a. NH3 is a strong conjugate base

in the reaction above, NH4+ acts as a weak acid. Which of the following must be true?

d. The same in all three containers

refer to three gases in identical, rigid containers under the conditions given in the table below for the next 2 questions. The average kinetic energy of the gas molecules is.

b. Fe(CO3)3

salts containing halide ions are soluble except for those containing silver, lead, and mercury. Salts containing carbonate anions are insoluble except for those containing alkali metals or ammonium. If solutions of iron III nitrate and sodium carbonate are mixed, what would be the formula of the precipitate?

d. 0.45

what is the expected absórbanle of a standard solution made by dissolving 0.0070 mol of NiCl2 • 6H2O in water to make 100. mL of solution.

d. 0.20 M

what is the molarity of I- in a solution that contains 34 g of SrI2 in 1.0 L of the solution?

d. 64 grams

what mass of oxygen is in 148 g of calcium hydroxide

b. 10

when a 3.22 g sample of an unknown hydrate of salt sodium sulfate,Na2SO4•H2O, is heated, H2O (molar mass 18 g) is driven off. The mass of the anhydrous Na2SO4 (molar mass 142 g) that remains is 1.42 g. the value of x in the hydrate is:

c. III only

A sample of an ideal gas is cooled from 50°C to 25° C in a sealed container of constant volume. Which of the following values for the gas will decrease.

b. The temperature of the reaction mixture increases

A student had two dilute, colorless solutions, HCl, and NaOH, which were at the same temperature. The student combined the solutions, and the reaction represented above occurred. Which of the following results would be evidence that a chemical reaction took place?

a. Infrared spectroscopy

A student placed a sample of a food coloring that contains a mixture of a blue dye, and a red dye at the top of a chromatography column filled with a nonpolar stationary phase. When water is poured through the column, two bands of colors are seen in the column, as shown in the diagram above. Which of the following techniques would be best to investigate molecular vibrations in molecules of the red dye

b. I2 and C6H14 have similar intermolecular interactions, and I2 and H2O do not.

A student places a piece of I2 in 50.0 mL of H2O, another piece of I2 of the same mass in 50.0 mL of C6H14, and shakes the mixtures. The results are shown above. What do the results indicate about the intermolecular interactions of the substances?

b. A fingerprint was left on the side of the cuvette facing the detector.

A student prepared for solutions of known [Cu2+] and measured the absorbance of each solution using the same cuvette. The graph shows the data for two absorbance measurements done for each solution. Which of the following identifies the most likely error that affected the absorbance recorded for the solution with [Cu2+]= 7 x 10^-3 M in the second trial?

a. 0.200 M

A student uses visible spectrophotometry to determine the concentration of CoCl2 in a sample solution. First, the student prepares a set of CoCl2 solutions of known concentration. Then the student uses a spectrophotometer to determine the absorbance of each of the standard solutions at a wavelength of 510 nm and constructs a standard curve. Finally, the student determines the absorbance of the sample of unknown concentration. The original solution used to make the solutions for the standard curve was prepared by dissolving 2.60 g of CoCl2 in enough water to make 100 mL of solution. What is the molar concentration of the solution?

d. 4 x 10^-19 J

A wave length of 510 nm corresponds to an approximate frequency of 6 x 10^14 s^-1. what is the approximate energy of one photon of this light?

d. it is a redox reaction, because Cu is oxidized and the nitrogen atom in NO3- is reduced

each student in a class placed a 2.00 g sample of a mixture of Cu and Al in a beaker and placed the beaker in a fume hood. The students slowly poured 15.0 mL of 15.8 M HNO3 into their beakers. The reaction between the copper in the mixture and the HNO3 is represented by the equation above. The students observed that a brown gas was released from the beakers and that the solutions turned blue, indicating the formation of Cu2. The solutions were then diluted with distilled water to known volumes. Which of the following is true about the reaction?

c. BH3

has a central atom with less than an octet of electrons

a. H2O

has two lone pairs of electrons

a. 0.555 g

how many grams of CaCl2 are needed to prepare 100 mL of 0.100 M Cl- ions?

a. 0.20 g of H2

if 0.40 mol of H2 and 0.15 mol of O2 were to react as completely as possible to produce H2O, what mass of reactant would remain?

a. SO3

if a pure sample of an oxide of sulfur contains 40% sulfur and 60% oxygen by mass, then the empirical formula of the oxide is:

b. Set B

in the reaction represented above, which of the following sets correctly identifies the hybridization of the C atoms before and after the reaction occurs?

a. CrO4^2-

in which of the following compounds is the oxidation number of chromium the greatest?

a. 1.5

there are several different potential Lewis diagrams for the sulfate ion two of which are below. What is the overall bond order shown in structure B?

d. Reheat the sample until its mass is constant.

to determine the percentage of water in a hydrated salt, a student heated a 1.2346 g sample of the salt for 30 minutes; when cooled to room temperature, the sample weighed 1.1857 g. After the sample was heated for an additional 10 minutes and again cooled to room temperature, the sample weighed 1.1632 g. Which of the following should the student do next?

a. Equation A

use the four equations below for the following two questions. Choose the equation that represents an oxidation reaction that is also a synthesis reaction:

c. trigonal planar

what geometrical arrangement is associated with orbitals that are sp2 hybridized?

d. 4

when the equation above is balanced and all coefficients are reduced to lowest whole number terms, what is the coefficient for H3PO4?

d. Br

which element has the highest electronegativity?

a. NH3

which has a pyramidal shape?

b. :N - - - N - O (with 6 electrons around it)

which of the following Lewis diagrams best represents the bonding in the N2O molecule, considering formal charges?

a. NH3 molecules are polar while CH4 molecules are not, and the greater attractions between NH3 molecules cause the molecules to collide with the walls of the container with less force.

which of the following best helps explain why the pressure of a sample of CH4 is closer to the pressure predicted by the ideal gas law than a sample of NH3

b. Answer B

which of the following best represents the electron configuration for an atom of sulfur?

d. Cu2O

which of the following compounds contains an element in a +1 oxidation state, before you balance according to subscripts?

b. The acid is HNO2, and the conjugate base is NO2-

which of the following correctly identifies a Bronsted-Lowry conjugate acid-base pair in a solution prepared by mixing together HNO2 and NH3

b. Ar, because of its higher effective nuclear charge

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

c. Sr2+

which of the following ions has the same number of electrons as Br-?

d. 2Ag+ + Ni —> 2Ag + Ni2+

which of the following is the balanced net ionic equation for an oxidation reduction reaction between Ag+ and Ni based on the half reactions represented above?

b. NH3

which of the following is the conjugate acid of NH2-?

d. Equation D

which of the following is the net ionic equation for the reaction between aqueous sodium fluoride and hydrochloric acid?

b. 55,79,55

which of the following lists the correct number of protons, neutrons, and electrons (in that order) of a neutral cesium-134 atom?

d. CCl4

which of the following molecules contains polar covalent bonds but is a nonpolar molecule?

a. Br-F

which of the following molecules has the largest dipole moment?

a. N2

which of the following molecules has the shortest bond length?

b. CCl4

which of the following molecules is least soluble in water?

c. NO3- —> NO

which of the following represents a process in which a species is reduced?

d. The bond is highly polar

which of the following scientific claims about the bond in the molecular compound HF is most likely to be true?

d. The electrons in the anion have greater repulsion than those in the neutral atom.

why does an anion of phosphorous have a larger radius than a neutral atom of phosphorous?