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AP CHEMISTRY FINAL EXAM REVIEW ( Latest 2024 / 2025 ) Actual Questions and Answers 100% Correct
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AP CHEMISTRY FINAL EXAM REVIEW ( Latest 2024 / 2025 ) Actual Questions and Answers 100% Correct
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AP CHEMISTRY FINAL EXAM REVIEW• 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 theabsorbance of the sample of unknown concentration.
The original solution used to make the solutions for the standard curve wasprepared 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 thesolution?: A) 0.200M
Correct. Molarity =moles of solute/volume of solution=(2.60gCoCl/2100.mL)×(1mol-
CoCl2/130.gCoCl2)×(1000mL/1L)=0.200M
• The diagram above shows the distribution of speeds for a sample of N2(g) at 25°C. Which
of the following graphs shows the distribution of speeds for a sample of O2(g) at 25°C (dashed
line) ?: A) https://assets.learnosity.com/organisations/537/VH912643.g05.png
Correct. Two gases at the same temperature have molecules with the same average kinetic
energy. Since KE=1/2*mA*v2A=1/2*mB*v2B for two gases, AA and BB, the gas with the
higher molar mass will have molecules with a lower average speed.
This graph shows the O2(g)O2(g) molecules with a lower average speed than the
N2(g)N2(g) molecules.
• The electron cloud of HF is smaller than that of F2 , however, HF has a much higher
boiling point than F2 has.Which of the following explains how thedispersion-force model of
intermolecular attraction does not account for theunusually high boiling point of HF?: D)
Liquid F2F2 has weak dispersion force attractions between its molecules, whereas liquid
HFHF has both weak dispersionforce attractions and hydrogen bonding interactions between
its molecules.
Correct. The hydrogen bonding interactions in HFHF are much stronger than theweak
dispersion forces between F2F2 molecules.
• How many moles of Na+ ions are in 100.mL of 0.100MNa3PO4(aq) ?: -
C)0.0300molCorrect. Na3PO4Na3PO4 forms three Na+Na+ ions per formula unit when it
dissociates in water. 100mL100mL of 0.100MNa3PO40.100MNa3PO4 contains
100mL×0.100mol/1000mL=0.0100mol100mL×0.100mol/1000mL=0.0100molof
Na3PO4Na3PO4, which dissociates into 0.0300mol0.0300mol of Na+Na+ ions.
• The survival of aquatic organisms depends on the small amount of O2 thatdissolves in
H2O. The diagrams above represent possible models to explain this phenomenon. Which
, diagram provides the better particle representationfor the solubility of O2 in H2O, and why?:
C) Diagram 2, because the polar H2OH2O molecules can induce temporary dipoles on the
electron clouds of O2O2molecules.
Correct. The relatively small solubility of O2O2 in water is due to dipole-induced dipole
forces between the polar H2OH2O molecules and the nonpolar O2O2 mole-cules. The
permanent dipole moment of the H2OH2O molecules induces temporarydipole moments on
the electron clouds of the nonpolar O2O2 molecules.
• Diagram 1 above shows equimolar samples of two gases inside a containerfitted with a
removable barrier placed so that each gas occupies the same volume. The barrier is carefully
removed as the temperature is held constant.Diagram 2 above shows the gases soon after the
barrier is removed. Which statement describes the changes to the initial pressure of each gas
and the final partial pressure of each gas in the mixture and also indicates the final total
pressure?: C) The partial pressure of each gas in the mixture is half its initialpressure; the final
total pressure is half the sum of the initial pressures of the two gases.
Correct. For each gas, the partial pressure in the mixture is half its initial pressurebecause the
volume occupied has doubled under constant nn and TT. Since P±1V×constantP±1V×constant,
Pf=12×PiPf=12×Pi for each gas. According to Dalton's law, the final total pressure (PTf)(PTf)
is given by
PTf=Pf,gas1+Pf,gas2=12(Pi,gas1+Pi,gas2)PTf=Pf,gas1+Pf,gas2=12(Pi,gas1+Pi,gas2
18. 2F2(g)+2NaOH(aq)’OF2(g)+2NaF(aq)+H2O(l)
A 2mol sample of F2(g) reacts with excess NaOH(aq) according to the equationabove. If the
reaction is repeated with excess NaOH(aq) but with 1 mol of F2(g),which of the following is
correct?: B) The amount of OF2(g)OF2(g) produced ishalved.
Correct. The NaOH(aq)NaOH(aq) is in excess. If the amount of reactants is halved, the amount
of each product is halved. The coefficients in the equation do not need to be taken into account
in this case.
• Two different ionic compounds each contain only copper and chlorine. Bothcompounds are
powders, one white and one brown. An elemental analysis
is performed on each powder. Which of the following questions about the compounds is most
likely to be answered by the results of the analysis?: B)What is the formula unit of each
compound?
Correct. From the elemental analysis, the moles of copper and chlorine can be calculated, then
the mole ratio of copper to chlorine can be calculated. This ratiois the formula unit of the ionic
compound.
• The mass spectrum of the element Sb is most likely represented by which ofthe following?: B)
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