ap chem unit 3 mcq

Solid Al(NO3)3 is added to distilled water to produce a solution in which the concentration of nitrate, [NO -], is 0.10 M. What is the concentration of aluminum ion, [Al3+], in this solution?

0.033M

Of the three solutions listed in the table above, which one, if any, has the greatest electrical conductivity and why?

0.1M Kl(aq) because Kl completely dissociates in water to produce ions

The original solution used to make the solutions for the standard curve was prepared by dissolving 2.60g of CoCl2 (molar mass 130.g/mol) in enough water to make 100.mL of solution. What is the molar concentration of the solution?

0.200 M

How many grams of CaCl2 (molar mass = 111g/mol) are needed to prepare 100 mL of 0.100M CL- (aq) ions?

0.555g

How many mL of10.0 MHCl are needed to prepare 500. mL of 2.00 MHCl ?

100 mL

The volume of water that must be added in order to dilute 40 mL of 9.0 MHCl to a concentration of6.0 Mis closest to

20 mL

Which of the following pieces of laboratory glassware should be used to most accurately measure out a 25.00 mL sample of a solution?

25 mL pipet

Equal masses ofHe and Ne are placed in a sealed container. What is the partial pressure ofHe if the total pressure in the container is 6 atm?

5 atm

If the pressure of each gas is increased at constant temperature until condensation occurs, which gas will condense at the lowest pressure?

Butane

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

CCl4

Which of the following molecules is nonpolar but has polar covalent bonds?

CCl4

In which of the following liquids do the intermolecular forces include dipole-dipole forces?

CH2F2 (l)

A 2 L container will hold about 4 g of which of the following gases at 0°C and 1 atm?

CO2

Which of the following is a nonpolar molecule that contains polar bonds?

CO2

A 1L sample of helium gas at 25ºC and 1 atm is combined with a 1L sample of neon gas at 25ºC and 1 atm. The temperature is kept constant. Which of the following statements about combining the gases is correct?

D) The average kinetic energy of the helium atoms and neon atoms do not change when the gases are combined.

Which of the following behaves most like an ideal gas at the conditions indicated?

H2(g) molecules at 10^-3 atm and 200oC

The experimental apparatus represented above is used to demonstrate the rates at which gases diffuse. When the cotton balls are placed in the ends of a tube at the same time, the gases diffuse from each end and meet somewhere in between, where they react to form a white solid. Which of the following combinations will produce a solid closest to the center of the tube?

HCl and CH3NH2

The diagram above shows molecules of Br2 and I2 drawn to the same scale. Which of the following is the best explanation for the difference in the boiling points of liquid Br2 and I2, which are 59ºC and 184ºC, respectively?

I2 molecules have electron clouds that are more polarizable than those ofBr2 molecules, thus London dispersion forces are stronger in liquid I2.

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?

Infrared spectroscopy

In solid methane, the forces between neighboring CH4 molecules are best characterized as

London (dispersion) forces

A 0.10 Maqueous solution of sodium sulfate, Na2SO4 , is a better conductor of electricity than a 0.10 Maqueous solution of sodium chloride, NaCl. Which of the following best explains this observation?

More moles of ions are present in a given volume of0.10 MNa2SO4 than in the same volume of 0.10 M NaCl.

Which of the following could be the identity of a white crystalline solid that exhibits the following properties? • It melts at 320°C. • It does not conduct electricity as a solid. • It conducts electricity in an aqueous solution.

NaOH (s)

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 Using the wavelength information provided above, what is the color of the light?

Orange

Which of the following substances is a strong electrolyte when dissolved in water?

Sodium nitrate

A student is given a sample of a pure, white crystalline substance. Which of the following would be most useful in providing data to determine if the substance is an ionic compound?

Testing the electrical conductivity of an aqueous solution of the substance

2 NO2(g) ⇄ N2O4(g) dark brown colorless The dimerization ofNO2(g) , an exothermic process, is represented by the equation above. The boiling points of the elements helium, neon, argon, krypton, and xenon increase in that order. Which of the following statements accounts for this increase?

The London (dispersion) forces increase.

Which of the following best helps to explain why CCl4 is a liquid whereas CI4 is a solid when both are at 25°C?

The London dispersion forces are stronger in CI4 than in CCl4 because CI4 has a more polarizable electron cloud than CCl4

CCl4 (g) deviates more from ideal gas behavior than CH4 (g) does. Which of the following statements best explains this observation?

The London dispersion forces between CCl4 molecules are stronger than those between CH4 molecules.

A rigid metal tank contains oxygen gas. Which of the following applies to the gas in the tank when additional oxygen is added at constant temperature?

The average speed of the gas molecules remains the same.

A student prepared five solutions ofCuSO4 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 used for the 0.600 M solution had not been wiped clean before being put in the spectrophotometer.

The diagram above represents a particle in aqueous solution. Which of the following statements about the particle is correct?

The particle must be an anion because the positive end of each water molecule is pointed toward it.

Ar(g) deviates more from ideal behavior at extremely high pressures than Ne(g) does. Which of the following is one reason for this difference?

The particle volume of Ar is greater than that of Ne.

A student collects a sample of the blue dye from the column in a cuvette. Which of the following is least useful to determine the concentration of the sample using a spectrophotometer set at 640nm?

The volume of the sample

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?

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

The best explanation for the fact that diamond is extremely hard is that diamond crystals

are giant molecules in which each atom forms strong covalent bonds with all of its neighboring atoms

Of the following, the best explanation for the fact that most gases are easily compressed is that the molecules in a gas

are relatively far apart

At standard temperature and pressure, a 0.50 mol sample of H2 gas and a separate 1.0 mol sample of O2 gas have the same

average molecular kinetic energy

At 298 K and 1 atm, bromine is a liquid with a high vapor pressure, whereas chlorine is a gas. This provides evidence that, under these conditions, the

forces among Br2 molecules are greater than those among Cl2 molecules

Questions refer to three gases in identical rigid containers under the conditions given in the table below. The density of the gas, in g/L, is

greatest in container B

A sample of a hard, solid binary compound at room temperature did not conduct electricity as a pure solid but became highly conductive when dissolved in water. Which of the following types of interactions is most likely found between the particles in the substance?

ionic bonds

A sample of an unknown gas from a cylinder is collected over water in the apparatus shown above. After all the gas sample has been collected, the water levels inside and outside the gas collection tube are made the same. Measurements that must be made to calculate the molar mass of the gas include all of the following EXCEPT

mass of the water in the apparatus

If the pressure of each gas is increased at constant temperature until condensation occurs, which gas will condenseat the lowest pressure?

Butane

The table above shows the structural formulas and molar masses for three different compounds. Which of the following is a list of the compounds in order of increasing boiling points?

Butane<acetone<1-propanol

The Lewis electron-dot diagram for C4H10 is shown above. Which of the following is the predominant type of intermolecular force among C4H10 molecules?

London dispersion forces

Which statement correctly compares what occurs when molecules absorb photons in the microwave region with what occurs when molecules absorb photons in the infrared region?

Microwave photons cause the molecules to increase their rotational energy states, whereas infrared photons cause the molecules to increase their vibrational energy states.

A vessel contains Ar(g) at a high pressure. Which of the following statements best helps to explain why the measured pressure is significantly greater than the pressure calculated using the ideal gas law?

The combined volume of the Ar atoms is too large to be negligible compared with the total volume of the container.

Which of the following best explains the increase in pressure of the C4H10 (g) when its volume is decreased from 0.5L to 0.21L?

The molecules strike the walls of the vessel more frequently.

The diagrams above show the ultraviolet absorption spectra for two compounds. Diagram 1 is the absorption spectrum of pure acetone, a solvent used when preparing solutions for an experiment. Diagram 2 is the absorption spectrum of the solute for which the absorbance needs to be measured to determine its concentration. When the student reads the absorbance of the solution at , the result is too high. Which of the following is most likely responsible for the error in the measured absorbance?

The student forgot to calibrate the spectrophotometer first by using a cuvette containing only acetone.

The student made the standard curve above. Which of the following most likely caused the error in the point the student plotted at 0.050M Co2+ (aq)?

There was distilled water in the cuvette when the student put the standard solution in it.

According to the VSEPR model, the progressive decrease in the bond angles in the series ofmolecules CH4, NH3, and H2O is best accounted for by the

increasing number of unshared pairs of electrons