AP Chemistry

An antacid tablet containing Mg(OH)2(s) (molar mass 58.3 g/mol) is titrated with a 0.100 M solution of HNO3(aq). The end point is determined by using an indicator. Based on the data in the table above, what was the mass of the Mg(OH)2(s)in the antacid tablet?

0.0583 g

Which of the following is the ground-state electron configuration of the F- ion? 1s22s22p4 1s22s22p5 1s22s22p6 1s22s22p63s1

1s^2 2s^2 2p^6

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(aq) into their beakers. The reaction between the copper in the mixture and the HNO3(aq) 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+(aq). The solutions were then diluted with distilled water to known volumes. The students determined that the reaction produced 0.010 mol of Cu(NO3)2 (aq). Based on the measurement, what was the percent of Cu by mass in the original 2.00 g sample of the mixture?

32%

When the equation for the reaction represented above is balanced and all coefficients are reduced to the lowest whole-number terms, the coefficient for O2(g) is 1 2 3 5 6

5

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

5atm

Steel is an alloy containing Fe atoms and C atoms. Which of the following diagrams best represents the particle-level structure of steel?

B - Big Fe small C

For element X represented above, which of the following is the most likely explanation for the large difference between the second and third ionization energies? The effective nuclear charge decreases with successive ionizations. The shielding of outer electrons increases with successive ionizations. The electron removed during the third ionization is, on average, much closer to the nucleus than the first two electrons removed were. The ionic radius increases with successive ionizations.

C- The electron removed during the third ionization is, on average, much closer to the nucleus than the first two electrons removed were.

Which of the following substances has bonds with the greatest ionic character? CCl4 CuCl2 CaCl2 NCl3

CaCl2

Atoms of Mg combine with atoms of F to form a compound. Atoms of which of the following elements combine with atoms of F in the same ratio? Li Ba Al Cl Ne

Cl

The graph above shows the speed distribution of molecules in a sample of a gas at a certain temperature. Which of the following graphs shows the speed distribution of the same molecules at a lower temperature (as a dashed curve)?

D- Higher dashed line and more to the left

A mixture containing equal numbers of moles of ethyl acetate and butyl acetate was separated using distillation. Based on the diagrams shown above, which of the following identifies the substance that would be initially present in higher concentration in the distillate and correctly explains why that occurs?

Ethyl acetate, because it has a shorter carbon chain and weaker London dispersion forces

The melting point of MgO is higher than that of NaF. Explanations for this observation include which of the following? I. Mg2+ is more positively charged than Na+ II. O2- is more negatively charged than F- III. The O2- ion is smaller than F- ion

I and II only

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 59℃ and 184℃, respectively?

I2 molecules have electron clouds that are more polarizable than those of Br2 molecules, thus London dispersion forces are stronger in liquid I2.

Which of the following Contains 1 sigma (σ) and 2 pi (π) bonds?

N2

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

NH3

Which of the following represents a process in which a species is reduced? Ca(s) → Ca2+(aq) Hg(l) → Hg22+(aq) Fe2+(aq) → Fe3+(aq) NO3-(aq) → NO(g) SO32-(aq) → SO42-(aq)

NO3-(aq) → NO(g)

Which of the following shows a precipitation reaction? 2 Mg(s) + O2 (g) → 2 MgO (s) Pb2+(aq) + CrO42-(aq) → PbCrO4(s) SO3(g) + 2 H2O(l) → H3O+(aq) + HSO4-(aq) 2 H2O(l) → 2H2(g) + O2(g) Ag+(aq) + 2 NH3(aq) → [Ag(NH3)2]+(aq)

Pb2+(aq) + CrO42-(aq) → PbCrO4(s)

The mass spectrum of element X is presented in the diagram below. Based on the spectrum, which of the following can be concluded about element X?

The atomic mass of X is between 90 and 92.

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?

The pressure of the gas

The geometry of the SO3 molecule is best described as

Trigonal planar