AP Chem Unit 1-4 MC #timetodie

The pressure, in atm, exerted by 1.85 mol of an ideal gas placed in a 3.00 L container at 35.0ºC is given by which of the following expressions?

(1.85)(.0821)(308)/3.00 atm

According to the data in the table below, what is the value of delta-H for the reaction?

-390 KJ

How many sigma and pi bonds are present in the following molecule?

11 sigma bonds and 1 pi bond

The volume of distilled water that should be added to 10.0 mL of 6.00 M HCl(aq) in order to prepare a 0.500 M HCl(aq) solution is approximately

110 mL

Which best represents a ground state electron configuration of the negative ion of a halogen?

1s2 2s2 2p6 3s2 3p6

Which electron configuration is consistent with the given PES?

1s2 2s2 2p6 3s2 3p6

Which of the following characteristics apply to PCl3? 1. nonpolar 2. polar bonds 3. trigonal pyramidal 4. sp2

2 and 3

Which of the following sets of quantum numbers is possible for a 3d electron?

3, 2, -2, 1/2

Which of the following lists substances F2, HCl, and HF in order of increasing boiling point?

3. F2 < HCl < HF

What is the average atomic mass of this element?

35.5

The central atom in XeF is surrounded by...

4 single bonds, no double bonds, and 2 lone pairs of electrons

One of the outermost electrons in a strontinum atom in the ground state can be described by which of the following sets of quantum numbers?

5, 0, 0, 1/2

Which are the first five ionization energies of silicon?

780, 1575, 14110, 15650, 16100

The enthalpy of vaporization of water is 40.7 kJ/mol. Which of the following best explains why the enthalpy of vaporization of methane is less than that of water?

A. Methane does not exhibit hydrogen bonding, but water does.

A volume of 1.0 L of a .5 molar solution of Na2S contains

B. 1 mole of Na+ and .5 moles of S2-

The student forgets to wipe the curvette before putting it in the colorimeter and leaves fingerprints on the glass side. How would this affect the final concentration?

B. The fingerprints would block the light leading to a higher absorbance value and a higher reported concentration.

Which of the following molecules is predicted to have the largest bond angle

BH3

Which gives a correct trend in size?

Be > Mg > Ca > Sr

Which of the following does not describe any of the molecules below?

Bent

(based on colorimetry graph) the student measures an unknown solution to have an absorbance of .25. What is its Cu2+ concentration?

C. .045 M (read graph)

Correct complete ionic equation for the reaction between aqueous solutions of ammonium sulfate and lead (II) nitrate?

C. 2NH4+ + SO4(2-) + Pb2+ + 2NO3- -> PbSO4(s) + 2NH4+(aq) +2NO3-(aq)

Identify which of the following is a reaction in which the same reactant undergoes both oxidation and reduction.

C. 3Br2 + 6 OH- -> 5 Br- + BrO3-(aq) + 3H2O

Write a balanced equation for the combustion of propene. How many mol of O2 are required for each mol of propene?

C. 4.5

A compound has an empirical formula of C2H4O and a molecular weight of 176 g/mol. What is its molecular formula?

C8H16O4

The molecule with 2 pi-bonds a. CO2 b. H2O c. CH4 d. C2H4 e. NH3

CO2

The melting point of CaO is higher than that of KF. Explanations for this observation include which of the following?

Ca2+ is more positively charged than K+, and O2- is more negatively charged than F-. (I and II Only)

The element that corresponds with the configuration 1s2 2s2 2p6 3s2 4s1 3d5 is

Chromium

What element is represented by the mass spectrum?

Cl

The electron pair in a C-F bond could be considered

Closer to F because fluorine has a higher electronegativity than carbon.

The elements in which of the following have the most nearly the same atomic radius?

Cr, Mn, Fe, Co

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

Cu -> Cu2+ and Ag+ + e- -> Ag

Select the precipitate that forms when the following reactants are mixed. Na2CO3(aq) + CuSO4(aq) ->

CuCo3

Which diagram correctly shows the partial charge of the oxygen atom and the orientation of water molecules being attracted to the ion of an ionic salt in an aqueous solution.

D. (the one with a positive center and negative surrounding molecules)

How many electrons are transferred in the reaction represented by the balanced equation: 2MnO4-(aq) + 10 Br- + 16 H+ -> 2 Mn2+(aq) + 5Br2 (aq) + 8H2)

D. 10

According to the balanced equation below, how many moles of HI would be necessary to produce 2.5 mol of I2 , starting with 4.0 mol of KMnO4 and 3.0 Mol of H2SO4?

D. 5.0 Mol H2SO4

Identify the precipitation reaction.

D. Ca2+ + SO4(2-) -> CaSO4-(s)

Which is a strong acid?

D. Perchloric acid

Lewis diagrams for CO2 and SO2 are given below. The molecular geometry and polarity of the two substances are

Different because S has a different number of electron domains

The atomic radius generally increases as we move

Down a group and from right to left across a period

In Bohr's atomic theory, when an electron moves from one energy level to another more distant from the nucleus:

Energy is absorbed

In the equation Fe(OH)2 + CrO4(2-) -> Fe2O3 + Cr(OH)4-, what is the reducing agent?

Fe(OH)2

Most electronegative element?

Fluorine

In which structure does the oxygen have a formal charge of +1?

I, III, and IV

Types of hybridization exhibited by the C atoms in propene, CH3CHCH2, include which of the following? I. sp II. sp2 III. sp3

II and III Only

The progressive decrease in the bond angles in the series of molecules CH4, PH3, and H2S is best accounted for by the

Increasing number of unshared pairs of electrons

The correct name for FeSO3 is

Iron (II) Sulfite

What happens to chromium in the reaction from #98?

It is reduced, gaining three electrons

Which of these salts is soluble?

K2SO4

A compound contains 1.1 mol of K, 1.65 mol of O, and .55 mol of Te. What is the simplest formula of this compound?

K2TeO3

Which of the following best describes the energy required to convert a ground-state atom in the gas phase to a gaseous positive ion?

Lattice energy

Which describes why O has less first ionization energy than N?

Less energy is required to remove an electron from an O atom due to the fact that O only has one doubly-occupied 2p orbital and nitrogen does not.

All of the following are IMFs. Which exist in every single species?

London dispersion

Atoms of an element, X, have the electron configuration 1s2 2s2 2p6 3s2 3p 4. The compound most likely formed with Mg is...

MgX

The first five I.E.s of a second-period element are listed. Which best explains the data?

N, because it has three valence electrons in the P sublevel

Which of the following arranges the molecules F2, N2, and O2 in order of bond length, from least to greatest?

N2 < F2 < O2

Which of the following arranges the molecules F2, N2, and O2 in order of their bond lengths, from least to greatest?

N2 < O2 < F2

The Lewis dot structure of which of the following molecules shows only one unshared pair of valence electrons?

NH3

The molecule that has trigonal pyramidal geometry a. CO2 b. H2O c. CH4 d. C2H4 e. NH3

NH3

Which of the following compounds is ionic and contains both sigma and pi bonds?

NaCN

Diamagnetic Element?

Neon

Largest ionic size?

Nitrogen

Which is incorrectly named?

No3-, nitrite ion

Of the following single bonds, which is the LEAST polar?

O-F

Resonance is most commonly used to describe the bonding in molecules of which of the following?

O3

Smallest atomic radius?

Oxygen

The PES of an unknown element is shown. It is...

Phosphorous

Which is utilized to determine the energy of core electrons?

Photoelectron Spectroscopy

Which of the following does not behave like an electrolyte in water?

Propane

Which of the following are isoelectronic?

S2-, K+, Ca2+

What is the hybridization of the carbon atoms in a molecule of ethyne?

SP

Which of the following choices correctly identifies the hybridization of the central atom and the molecular geometry of Nitrogen Trifluoride

SP3, trigonal pyramidal

What hybridization change does the carbon atom undergo in the combustion of methane?

SP3->sp

Which atom contains exactly three unpaired electrons?

Sb - Antimony

Which arranges the binary compounds in order of increasing bond polarity?

SiH4 < SCl4 < CF4

A chemist wants to produce a precipitate. This can be accomplished by mixing BaCl2 and

Sodium Sulfate, Na2SO4

Which of the following is true regarding the reaction represented above?

The oxidation number of Se changes from -2 to +6.

Benzene, C6H6, has the structure shown above. Considering the observation that benzene is only sparingly soluble in water, which of the following best described the intermolecular forces of attraction between water and benzene?

There are dipole-induced dipole and London dispersion interactions between water and benzene.

Which of the following helps to explain why the electron affinity of Bromine has a greater magnitude than that of Iodine?

There is greater attraction between an added electron and the nucleus in Bromine than in Iodine.

The geometry of the SO3 molecule is best described as

Trigonal planar

Which has the shortest wavelength, the greatest energy, and the highest frequency?

UV radiation

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

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

Which of the following is not a postulate of the kinetic molecular theory?

a. Gas particles have most of their mass concentrated in the nucleus of the atom.

A .5 mol sample of He(g) and a .5 mol sample of Ne(g) are placed separately in two 10.0 L rigid containers at 25 degrees C. Each container has a pinhole opening, which of the gases, He(g) or Ne(g), will escape faster through the pinhole and why?

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

Which of the following best helps explain why the pressure of a sample of CH4 (molar mass 16 g/mol) is closer to the pressure predicted by the ideal gas law than a sample of NH3 (molar mass 17 g/mol)?

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

Which of the following statements accounts for the increase in boiling points among the noble gases?

a. The London dispersion forces increase

Which of the following is true of the triple point of a pure substance?

a. The vapor pressure of the solid phase always equals the vapor pressure of the liquid phase.

The molecule with the largest dipole moment a. CO2 b. H2O c. CH4 d. C2H4 e. NH3

b. H2O

When a sample of oxygen gas in a closed container of constant volume is heated until its absolute temperature is doubled, which of the following is also doubled?

b. The pressure of the gas

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

c. 500 K and .1 ATM

Based on the data in the table below, which of the following liquid substances has the weakest IMFs?

c. CH3OH (you can tell from the data b/c it has the highest vapor pressure and vapor pressure is inversely proportional to IMF strength)

Which of the following best accounts for HF having the highest boiling point?

c. Hydrogen bonding

Which statement best helps to explain the observation that NH3(l) boils at -28 degrees C but PH3(I) boils at -126 degrees c?

c. NH3 has hydrogen bonding that is stronger than the dipole-dipole forces in PH3.

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

c. The average speed of the gas molecules remains the same.

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 increase?

c. The average speed of the molecules

Which of the following statements best accounts for the differences in solubility among the noble gases?

c. The gases become more soluble as molar mass increases because they become more polarizable thus the amount of dipole-induced dipole forces increases.

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 280 nm, the result is too high. Which of the following is most likely responsible for the error in measured absorbance?

c. The student forgot to calibrate the spectrophotometer first by using a curvette containing acetone.

A student wishes to prepare 2.00 liters of 0.100-molar KIO3 (molecular weight 214). The proper procedure is to weigh out

d. 42.8 grams of KIO3 and add H2O until the final homogeneous solution has a volume of 2 L

Which of the following has an average atomic or molecular speed closest to that of N2 molecules at 0°C and 1 atm?

d. CO

The ideal gas law best describes the properties of which of the following gases at 0 degrees C and 1 atm?

d. He

Explain why MgO(s) is not able to conduct electricity, but MgO(l) is a good conductor of electricity.

d. MgO(s) consists of separate Mg2+ ions and O2- ions held in a fixed lattice, but in MgO(l) the ions are free to move and conduct electricity.

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?

d. Testing the electrical conductivity of an aqueous solution of the substance

Equal numbers of moles of CO2, N2, an NH3 are placed in a sealed vessel at room temperature. If the vessel has a pinhole-sized leak, which of the following will be true after some of the gas mixture has effused?

d. The mole fraction of CO2 in the sample will increase.

The graph below shoes the distribution for four different gases at the same temperature. What property of the gases can be correctly ranked using information from the graph, and why?

d. The molecular masses of the gases, because the gas molecules have the same average kinetic energy and mass and can be calculated using the equivalent KE = 1/2mv.

Which of the following accounts for why physical properties do not differ much among gaseous compounds?

d. The relative distance between gas molecules is so large that there are virtually no IMFs, resulting in little variation in physical properties.

What is the pressure exerted by some nitrogen gas collected in a tube filled with water on a day when the room temperature is 18°C and the room pressure is 750 mmHg? [The partial pressure of the water at 18°C is 15.5 mmHg.]

e. 734.5 mmHg

Select the correct name and formula for the precipitate that forms when the following reactants are mixed. CoSO4 + (NH4)3PO4 ->

e. Ammonium sulfate, (NH4)2SO4

A gaseous mixture at a constant temperature contains O2, CO2, and He. Which of the following lists the three gases in order of increasing average molecular speeds?

e. Co2, O2, He

The SbCl5 molecule has a trigonal bypyramidal structure. Therefore, the hybridization of Sb orbitals should be

sp3d

Which represents the ground state orbital notation for the valence electrons of nitrogen?

up/down, up up up