AP Test Review 1
(Units 1-5)
Atoms
Bonds
IMF’s
Reactions
Kinetics
Answer: Mg3X2
200
Topic 1.5
1s2 2s2 2p6 3s2 3p3
Atoms of an element, X, have the electronic configuration shown above. What is the formula most likely formed when Mg and X form a compound?
400
Answer: C2H6O
Topic 1.3
A 23.0g sample of a compound contains 12.0g of C, 3.0g of H, and 8.0g of O. What is the empirical formula of the compound?
600
Answer: The valence shell of Cl is higher energy than F so valence electrons have weaker attraction to nucleus according to Coulomb’s Law due to larger distance.
Topic 1.7
Why is the electronegativity of Cl less than that of F?
800
Answer: Cl<P<Mg
Topic 1.7
List the following elements in order of increasing atomic radius: Mg, P, and Cl.
1000
Answer: NaI has larger ions and smaller ionic charges
Topic 1.8
Explain why give two reasons why NaI has a lower lattice energy than BeCl2.
200
Answer: 1 σ and 2 π
Topic 2.7
How many sigma and pi bonds exist between the carbon atoms?
400
Answer: London dispersion forces
Topic 3.1
Solid CCl4 is represented by the diagram below. What is holding the molecules together as a solid?
600
Answer: Increase in the number of lone pairs on central atom
Topic 2.7
According to the VSEPR model, why is there a progressive decrease in the bond angles in the series of molecules CH4, NH3, and H2O.
800
Answer: +1
Topic 2.6
What is the formal charge of the oxygen atom on the left in the following Lewis structure?
1000
Answer: Yes, from sp to sp2
Topic 2.7
C2H2(g) + Cl2(g) → C2H2Cl2(g)
Does the hybridization of the carbon atoms change, and if so from what to what?
200
Answer: Na2SO4 dissociates into more ions than NaCl
Topic 3.7
Why is a 0.10 M aqueous solution of sodium sulfate, Na2SO4 , a better conductor of electricity than a 0.10 M aqueous solution of sodium chloride, NaCl.
400
Answer: molecular
Topic 3.2
A certain crystalline substance that has a low melting point does not conduct electricity in solution or when melted. What type of solid is this?
600
Answer: Br2 (more polarizable due to more electrons)
Topic 3.1
On the basis of strength of intermolecular forces, which of the following elements would be expected to have the highest melting point?
A) Br2 B) Cl2 C) F2 D) Kr E) N2
800
Answer: 0.0300 mol
Topic 3.7
How many moles of Na+ ions are in 100. mL of 0.100 M Na3PO4(aq)?
1000
Answer: increase polarity of solvent
The diagram below shows a thin-layer chromatogram of a mixture of products from a chemical reaction. The separation was performed using 50% ethyl acetate in hexane as the solvent (mobile phase) and silica gel as the polar stationary phase. On the bases of the chromatogram and the info about solvents in the table, how could you modify the solvent to DECRASE the distance
that the products travel up the plate?
Topic 3.9
200
Answer: Pb2+(aq) + 2 Br-(aq) -> PbBr2(s)
Topic 4.2
Equal volumes of 0.20 M solution of lead(II) nitrate and potassium bromide are combined. What is the net ionic equation for this reaction?
400
Answer: 2
Topic 4.9
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?
600
Answer: 0.015 mol
Topic 4.5
3 Ag(s) + 4 HNO3 → 3 AgNO3 + NO(g) + 2 H2O
The reaction of silver metal and dilute nitric acid proceeds according to the equation above. If 0.10 mole of powdered silver is added to 10. milliliters of 6.0–molar nitric acid, the number of moles of NO gas that can be formed is
800
Answer: oxidation-reduction rxn
Topic 4.7
When C2H4(g) reacts with H2(g), the compound C2H6(g) is produce. Is this reaction correctly identified as a acid-base reaction, a preceipitation reaction, a decomposition reaction, or an oxidation-reduction reaction?
1000
Answer: NH3
Topic 4.8
What is the conjugate acid of NH2-?
200
Answer: C
Topic 5.8
2 A(g) + B(g) → 2 C(g)
When the concentration of substance B in the reaction above is doubled, all other factors being held constant, it is found that the rate of the reaction remains unchanged. The most probable explanation for this observation is that
A: the order of the reaction with respect to substance B is 1
B: substance B is not involved in any of the steps in the mechanism of the reaction
C: substance B is not involved in the rate–determined step of the mechanism, but is involved in subsequent steps
D: substance B is probably a catalyst, and as such, its effect on the rate of the reaction does not depend on its concentration
E: the reactant with the smallest coefficient in the balanced equation generally has little or no effect on the rate of the reaction
400
Answer: I, II, and III
Topic 5.5
Factors that affect the rate of a chemical reaction include which of the following?
I. Frequency of collisions of reactant particles
II. Kinetic energy of collisions of reactant particles
III. Orientation of reactant particles during collisions
600
Answer: rate = k[NO]2
Topic 5.8
2NO(g) + O2(g) -> N2O2(g)
A possible mechanism for the overall reaction represented above is the following:
1. NO(g) + NO(g) -> N2O2(g) slow
2. N2O2(g) + O2(g) -> 2NO2(g) fast
What is the rate law expression for the reaction that is consistent with the proposed mechanism?
800
Answer: Cl
Topic 5.7
The particle models shown below represent a proposed two-step mechanism for the destruction of ozone (O3) in the upper atmosphere.
Based on the models, what species acts as a catalyst for the reaction? (Write the symbol or formula for your answer.)
1000
Answer: 300 s
Topic 5.3
C25H30N3+(aq) + OH-(aq) -> C25H30N3OH(aq)
violet colorless
The reaction above is first order with respect to C25H30N3+(aq). A 10.0 mL sample of 0.10 M NaOH(aq) is mixed with a 10.0 mL sample of 2.5x10-5 M C25H30N3+(aq). A 5.0 mL sample of the mixture is quickly transferred to a clean cuvette and placed in a spectrophotometer, and the progress of the reaction is measured. The data are given in the table below. Approximately how long did it take for 75 percent of the initial amount of C25H30N3+(aq) to react?