Ap Chem sem 1

3 C2H2(g) → C6H6(g) What is the standard enthalphy change ΔHo, for the reaction represented above? (ΔHof of C2H2(g) is 230 kJ mol-1; (ΔHof of C6H6(g) is 83 kJ mol-1;) A)-607kj B)-147kj C)-19kj D)19kj E)773kj

-607kj

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)0.20g of H2 B)0.40g of H2 C)3.2g of O2 D)4.0g of O2 E)4.4gof O2

0.20g or H2

C10H12O4S(s) + . . . O2(g) → . . . CO2(g) + . . . SO2(g) + . . . H2O(g) When the equation above is balanced and all coefficients are reduced to their lowest whole-number terms, the coefficient for O2(g) is A)6 B)7 C)12 D)14 E)28

12

Which of the following is the ground-state electron configuration of the F− ion? A)1s2 2s2 2p4 B)1s2 2s2 2p5 C)1s2 2s2 2p6 D)1s2 2s2 2p6 3s2 3p6

1s2 2s2 2p6

Which of the following ground-state electron configurations represents the atom that has the lowest first-ionization energy? A)1s2 2s1 B)1s2 2s2 2p2 C)1s2 2s2 2p6 D)1s2 2s2 2p6 3s1

1s2 2s2 2p6 3s1

Al(s)→Al3+(aq)+3e− Zn2+(aq)+2e−→Zn(s) The half-reactions for the oxidation-reduction reaction between Al(s) and Zn2+(aq) are represented above. Based on the half-reactions, what is the coefficient for Al(s) if the equation for the oxidation-reduction reaction is balanced with the smallest whole-number coefficients? A)1 B)2 C)3 D)4

2

H2 + F2 → 2 HF In the reaction represented above, what mass of HF is produced by the reaction of 3.0 x 1023 molecules of H2 with excess F2 ? (Assume the reaction goes to completion.) A)1.0g B)4.0g C)10.g D)20.g E)20.g

20. g

In 1.00 mol of potassium zirconium sulfate trihydrate, K4Zr(SO4)4 • 3 H2O, there are A)3 × 6.02 × 1023 hydrogen atoms B)6.02 × 1023 sulfur atoms C)4 × 6.02 × 1023 potassium atoms D)4 moles of oxygen atoms E)4 moles of zirconium atoms

4 × 6.02 × 1023 potassium atoms

When 6.0 L of He(g) and 10. L of N2(g), both at 0oC and 1.0 atm, are pumped into an evacuated 4.0 L rigid container, the final pressure in the container at 0oC is A)2.0atm B)4.0atm C)6.4atm D)8.8atm E)16atm

4.0atm

A student uses visible spectrophotometry to determine the concentration of CoCl2(aq) in a sample solution. First the student prepares a set of CoCl2(aq) solutions of known concentration. Then the student uses a spectrophotometer to determine the absorbance of each of the standard solutions at a wavelength of 510nm and constructs a standard curve. Finally, the student determines the absorbance of the sample of unknown concentration. A wavelength of 510nm corresponds to an approximate frequency of 6×1014s−1. What is the approximate energy of one photon of this light? A)9x10^47 J B)3x10^17 J C)5x10^-7 J D)4x10^-19 J

4x10^-19 J

A hot iron ball is dropped into a 200. g sample of water initially at 50°C. If 8.4 kJ of heat is transferred from the ball to the water, what is the final temperature of the water? (The specific heat of water is 4.2 J/(g·°C). A)40 C B)51 C C)60 C D)70 C

60 C

½ H2(g) + ½ I2(s) → HI(g) ∆H = 26 kJ/molrxn ½ H2(g) + ½ I2(g) → HI(g) ∆H = -5.0 kJ/molrxn Based on the information above, what is the enthalpy change for the sublimation of iodine, represented below? I2(s) → I2(g) A)15 kJ/molrxn B)21 kJ/molrxn C)31 kJ/molrxn D)42 kJ/molrxn E)62 kJ/molrxn

62 kJ/molrxn

What is the percentage yield of O2 if 12.3 g of KClO3 (molar mass 123 g) is decomposed to produce 3.2 g of O2 (molar mass 32 g) according to the equation above? A)100% B)67% C)50% D)33% E)10%

67%

A student was studying physical and chemical changes. The student carried out some procedures in the laboratory and recorded observations. For one of the procedures, the student concluded that a physical change took place, but not a chemical change. Which of the following could have been the results of the procedure? A)A cube of metal was changed into a flat sheet of metal. B)When two liquids at room temperature were combined in a beaker, the beaker became hot C)When two clear liquids were combined, the resulting mixture was cloudy. D)When a colorless liquid was added to a blue liquid, the resulting solution was yellow.

A cube of metal was changed into a flat sheet of metal.

If equal masses of the following compounds undergo complete combustion, which will yield the greatest mass of CO2? A)Benzene, C6H6 B)Cyclohexane, C6H12 C)Glucose, C6H12O6 D)Methane, CH4

Benzene, C6H6

A 23.0g sample of a compound contains 12.0g of C, 3.0g of H, and 8.0g of O. Which of the following is the empirical formula of the compound? A)CH3O B)C2H60 C)C3H9O2 D)C4H12O2

C2H6O

A 2 L container will hold about 4 g of which of the following gases at 0°C and 1 atm? A)SO2 B)N2 C)CO2 D)C4H8 E)NH3

CO2

Each set of lettered choices below refers to the numbered statements immediately following it. Select the one lettered choice that best fits each statement. A choice may be used once, more than once, or not at all in each set. (A) Cs(B) Ag(C) Pb(D) Br(E) Se Has the largest atomic radius

Cs

Each set of lettered choices below refers to the numbered statements immediately following it. Select the one lettered choice that best fits each statement. A choice may be used once, more than once, or not at all in each set. (A) Cs(B) Ag(C) Pb(D) Br(E) Se Has the lowest first-ionization energy

Cs

Addition of sulfurous acid (a weak acid) to barium hydroxide (a strong base) results in the formation of a precipitate. The net ionic equation for this reaction is A)2 H+(aq) + 2 OH-(aq) ⇄ 2 H2O(l) B)H2SO3(aq) + Ba2+(aq) + 2 OH-(aq) ⇄ BaSO3(s) + 2 H2O(l) C)2 H+(aq) + SO32-(aq) + Ba2+(aq) + 2 OH-(aq) ⇄ BaSO3(s) + 2 H2O(l D)H2SO3(aq) + Ba2+(aq) + 2 OH-(aq) ⇄ Ba2+(aq) + SO32-(aq) + 2 H2O(l) E)H2SO3(aq) + Ba(OH)2(aq) ⇄ BaSO3(s) + 2 H2O(l)

H2SO3(aq) + Ba2+(aq) + 2 OH-(aq) ⇄ BaSO3(s) + 2 H2O(l)

Two pure elements react to form a compound. One element is an alkali metal, X, and the other element is a halogen, Z. Which of the following is the most valid scientific claim that can be made about the compound? A)It has the formula XZ2. B)it does not dissolve in water. C)it contains ionic bonds D)it contains covalent bonds

It contains ionic bonds Ionic compounds containing alkali metal ions are generally quite soluble in water.

The effective nuclear charge experienced by the outermost electron of Na is different than the effective nuclear charge experienced by the outermost electron of Ne. This difference best accounts for which of the following? A)Na has a greater density at standard conditions than Ne. B)Na has a lower first ionization energy than Ne C)Na has a higher melting point than Ne. D)Na has a higher neutron-to-proton ratio than Ne. E)Na has fewer naturally occurring isotopes than Ne.

Na has a lower first ionization energy than Ne

The reaction between aqueous strontium chloride (SrCl2) and aqueous potassium sulfate (K2SO4)forms a precipitate of strontium sulfate (SrSO4). Which of the following represents the net ionic equation for the reaction? A)Cl−(aq)+K+(aq)→KCl(aq) B)Sr2+(aq)+SO42−(aq)→SrSO4(s) C)Sr2+(aq)+2Cl−(aq)+SO42−(aq)+2K+(aq)→SrSO4(s)+2Cl−(aq)+2K+(aq) D)SrCl2(aq)+K2SO4(aq)→SrSO4(s)+2KCl(aq)

Sr2+(aq)+SO42−(aq)→SrSO4(s)

After completing an experiment to determine gravimetrically the percentage of water in a hydrate, a student reported a value of 38 percent. The correct value for the percentage of water in the hydrate is 51 percent. Which of the following is the most likely explanation for this difference? A)Strong initial heating caused some of the hydrate sample to spatter out of the crucible. B)The dehydrated sample absorbed moisture after heating. C)The amount of the hydrate sample used was too small. D)The crucible was not heated to constant mass before use. E)Excess heating caused the dehydrated sample to decompose.

The dehydrated sample absorbed moisture after heating

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 A)average molecular kinetic energy B)average molecular speed C)volume D)effusion rate E)density

average molecular kinetic energy

2 N2H4(g) + N2O4(g) → 3 N2(g) + 4 H2O(g) When 8.0 g of N2H4 (32 g mol-1) and 92 g of N2O4 (92 g mol-1) are mixed together and react according to the equation above, what is the maximum mass of H2O that can be produced? A)9.0g B)18g C)36g D)72g E)144g

9.0g

The table below contains information about samples of four different gases at 273 K. The samples are in four identical rigid containers numbered 1 through 4.The best explanation for the lower pressure in container 4 is that SO2 molecules A)have a larger average speed than the other three gases B)occupy a larger portion of the container volume than the other three gases C)have stronger intermolecular attractions than the other three gases D)containπbonds,while the other gases contain only σ bonds

have stronger intermolecular attractions than the other three gases

Potassium hydrogen phthalate, KHP, is used as a primary standard for determining the concentration of a solution of NaOH by titration. If the KHP has not been dried before weighing, the calculated molarity of the NaOH would be A)higher than the actual value, since water is included in the apparent mass of KHP B)higher than the actual value, since the presence of water requires a larger volume of titrant C)lower than the actual value, since NaOH absorbs water D)unaffected, since KHP is a strong acid E)unaffected, since water is routinely added before the titration

higher than the actual value, since water is included in the apparent mass of KHP

When the actual gas volume is greater than the volume predicted by the ideal gas law, the explanation lies in the fact that the ideal gas law does NOT include a factor for molecular. A)volume B)mass C)velocity D)attractions E)shape

volume

Which of the following is the best piece of laboratory glassware for preparing 500.0 mL of an aqueous solution of a solid? A)volumetric flask B)erlenmeyer flask C)test tube D)graduated beaker E)graduated cylinder

volumetric flask