AP Chemistry Final (Second Semester)

The process of dissolution of NaCl in H2O is represented in the diagram above. Which of the following summarizes the signs of H and S for each part of the dissolution process? (diagram '17 #34) answers in book

+ + + + - -

What is the value of the enthalpy change per mole of HCl produced? (explanation '17 above #42) -93 kJ -121 kJ -186 kJ -242 kJ

-93 kJ

Based on the bond energies listed in the table above, which of the following is closest to the bond energy of the C-N bond? (diagram '17 #37) 200 kJ/mol 300 kJ/mol 400 kJ/mol 500 kj/mol

300 kJ/mol

On the basis of the pH curve, the pKa value of the acid is closest to (explanation '17 above #55) 4 5 8 12

5

Which of the following best describes the change that takes place immediately after the CH3OH is introduced into the previously evacuated vessel? (diagram '18 #14) A chemical change takes place because covalent bonds are broken A chemical change takes place because intermolecular attractions are overcome A physical change takes place because covalent bonds are broken A physical change takes place because intermolecular attractions are overcome

A physical change takes place because intermolecular attractions are overcome

Equal volumes of 0.1M AgNO3 and 2M NH3 are mixed and the reactions represented above occur. Which Ag species will have the highest concentration in the equilibrium system shown below, and why? (diagrams '17 #47) Ag because Keq3 = 4 Ag because Keq1 < Keq2 Ag(NH3)2 Because Keq3 = 1.6E7 Ag(NH3)2 because Keq1 < Keq2

Ag(NH3)2 Because Keq3 = 1.6E7

The first ionization energy of an element is the energy required to remove an electron from a gaseous atom of the element. The values of the first ionization energies for the third row elements are shown in the graph above. On the basis of the information given, which of the following reactions is exothermic? (diagram '17 #6) Cl(g) + Mg(g) --> Cl + Mg(g) Al(g) + Mg(g) --> Ag(g) + Mg(g) P(g) + Mg(g) --> P(g) + Mg(g) S(g) + Mg(g) --> S(g) + Mg(g)

Al(g) + Mg(g) --> Ag(g) + Mg(g)

The compound CCl4 is nonflammable and was once commonly used in fire extinguishers. On the basis of periodic properties which of the following compounds can most likely be used as a fire-resistant chemical? BCl3 CH4 CBr4 PbCl2

CBr4

The complete photoelectron spectra of neutral atoms of two unknown elements, X and Y, are shown above. Which of the following can be interpreted from the data? (diagram '17 #19) Element X has a greater electronegaitivity than element Y does Element X has a greater ionization energy than element Y does Element Y has a greater nuclear charge than element X does The isotopes of element Y are approximately equal in abundance, but those of element X are not

Element Y has a greater nuclear charge than element X does

A student prepares a solution by combining 100mL of .3M HNO2 and 100 mL of .3M KNO2. Which of the following equations represents the reaction that best helps explain why adding a few drops of 1M HCl does not significantly change the pH of the solution? K + Cl --> KCl HNO2 --> H + NO2 H + OH --> H2O H + NO2 --> HNO2

H + NO2 --> HNO2

Which of the following has the bonds arranged in order of decreasing polarity? H - F > N - F > F - F H - I > H - Br > H - F O - Se > O - S > O - Te Sb - I > Sb - Te > Sb - Cl

H - F > N - F > F - F

Which of the following is the strongest type of interaction that occurs between the atom within the circled areas of the two molecules represented above? (diagram '17 #51) Polar covalent bond Nonpolar covalent bond Hydrogen bond London dispersion forces

Hydrogen bond

Which of the following is true about the reaction? (explanation '17 #10) It is a Bronsted-Lowry acid-base reaction, because the solution is neutral at the end It is a Bronsted-Lowry acid-base reaction, because HNO3(aq) is a strong acid It is a redox reaction, because Cu(s) is oxidized and H(aq) is reduced It is a redox reaction, because Cu(s) is oxidized and the nitrogen atom in NO3(aq) is reduced

It is a redox reaction, because Cu(s) is oxidized and the nitrogen atom in NO3(aq) is reduced

Under which of the following temperature conditions is the reaction thermodynamically favored? (explanation '17 #36) It is only favored at high temperatures It is only favored at low temperatures It is favored at all temperatures It is not favored at any temperature

It is not favored at any temperature

The decomposition of O3(g) in the upper atmosphere is represented by the equation above. The potential energy diagram for the decomposition of O3(g) in the presence and absence of NO(g) is given below. Which of the following mechanisms for the catalyzed reaction is consistent with the equation and the diagram above? (diagram '17 #32) equations listed in book

O3 + NO --> NO2 + O2 slow NO2 + O --> NO + O2 fast

Based on the information in the table to the left, which of the compounds has the highest boiling point, and why? (diagram '18 #4) Butanal, because it can form intermolecular hydrogen bonds Pentane, because it has the longest carbon chain Pentaine, because it has the most C - H bonds Propanoic acid, because it can form intermolecular hydrogen bonds

Propanoic acid, because it can form intermolecular hydrogen bonds

If a pure sample of oxide sulfur contains 40% sulfur and 60% oxygen by mass, then the empirical formula of the oxide is SO3 SO4 S2O6 S2O8

SO3

See 2018 #3

See 2018 #3

A 20 mL sample of .5M HC2H3O2 is titrated with .5 M NaOH. Which of the following best represents the species that react and the species produced in the reaction? See equations in book ('18 #7)

See equations in book ('18 #7)

What will be the effect on the amount of gas produced if the experiment is repeated using .35g of K instead of .35g of Li? (explanation '17 above #55) No gas will be produced when K is used Some gas will be produced but less than the amount of gas produced with Li Equal quantities of gas will be produced with the two metals More gas will be produced with K than with Li

Some gas will be produced but less than the amount of gas produced with Li

The equilibrium system represented by the equation above initially contains equal concentrations of Cr2O7 and CrO4. Which of the following statements correctly predicts the result of adding a sample of 6M NaOH to the system, and provides an explanation? The mixture will become more orange because OH will oxidize the Cr in CrO4 The mixture will become more yellow because OH will reduce the Cr in Cr2O7 The mixture will become more yellow because OH will shift the equilibrium toward products The color of the mixture will not change because OH does not appear in the equilibrium expression

The mixture will become more yellow because OH will shift the equilibrium toward products

Which of the following statements identifies the greatest single reason that the value of Kp for the overall reaction at 298 K has such a large magnitude? (explanation '17 #42) The activation energy for step 1 of the mechanism is large and positive The activation energy for step 2 of the mechanism is small ans positive The value of S for the overall reaction is small and positive The value of H for the overall reaction is large and positive

The value of H for the overall reaction is large and positive

Mg(OH)2 <--> Mg + 2OH The exothermic dissolution of Mg(OH)2 in water is represented in the equation above. The Ksp of Mg(OH)2 is 1.8E-11. Which of the following changes will increase the solubility of Mg(OH)2 in an aqueous solution? decreasing the pH increasing the pH adding NH3 to the solution adding Mg(NO3)2 to the solution

decreasing the pH

NH3 reacts with BF3 to form a single species. Which of the following structural diagrams is the most likely representation of the product of the reaction? Diagrams '17 #30

diagrams '17 #30

2NOBr --> 2NO + Br2 The equation above represents an elementary step in a chemical reaction. Which of the following is the correct expression for the rate law of the elementary step? r = k[NOBr]^1/2 r = k[NOBr] r = k[NOBr]^2 r = k[NO]^2[Br2]

r = k[NOBr]^2

'17 number 35 see book

see book

What are the relative strengths and acids of the bases in the reaction represented in the equation above? (diagram '17 #46) see book

see book

Which of the following is the balanced net ionic equation for the reaction between Li and water? see book for equations #58

see book

In the reaction represented above, what is the hybridization of the C atoms before and after the reaction occurs? (diagram '17 #7) Before After sp sp2 sp sp3 sp2 sp sp2 sp3

sp2 sp3

The value for Kp for the evaporation of CH3OH at 300K is closest to (diagram '18 above #14) .04 .2 5 30

.2

Based on the thermodynamic data, which of the following is true at 298 K? (diagram '17 above #37) Keq = 0 0< Keq < 1 Keq = 1 Keq >1

0 < Keq < 1

Based on the information in the table above, which of the following shows the cell potential and Gibbs free energy charge for the overall reaction that occurs in a standard galvanic cell? (diagram '17 #31) Ecell G 1.63 -157 1.63 -944 5.63 -543 5.63 -3262

1.63 -944

On the basis of the information above, what is the percent ionization of HNO2 in a 1M HNO2 solution? (diagram '18 #11) .0004% .02% .04% 2%

2%

A 1L sample of a pure gas is found to have a lower pressure than predicted by the ideal gas law. The best explanation for the observation is that the molecules of gas Have a combined volume that is too large to be considered negligible when compared to the volume of the container Have a low molecular mass and therefore do not strike the container walls with as much force as expected Are attracted to each other and do not exert as much force on the container walls as they would if they had no mutual attractions Are attracted to the sides of the container and strike the container walls with more force than expected

Are attracted to each other and do not exert as much force on the container walls as they would if they had no mutual attractions

An acetate buffer solution is prepared by combining 50 mL of 0.20 M acetic acid, HC2H3O2(aq), and 50 mL 0f 0.20 M sodium acetate, NaC2H3O2(aq). A 5.0 mL sample of 0.10 M NaOH(aq) is added to the buffer solution. Which of the following is a correct pairing of the acetate species present in greater concentration and of the pH solution after the NaOH is added? (the pKa of acetic acid is 4.7) Acetate species pH HC2H3O2 <4.7 HC2H3O2 >4.7 C2H3O2 <4.7 C2H3O2 >4.7

C2H3O2 >4.7

2H2O2 --> 2H2O + O2 The exothermic process represented above is classified as a Physical change because a new phase appears in the product Physical change because O2 that was dissolve come out of solution Chemical change because entropy increases as the process proceeds Chemical change because covalent bonds are broken and new covalent bonds are formed

Chemical change because covalent bonds are broken and new covalent bonds are formed

Based on the structures shown above, which of the following statements identifies the compound with the higher boiling point and provides the best explanation for the higher boiling point? (diagram '17 #20) Compound 1, because it has stronger dipole-dipole forces than compound 2 Compound 1, because it forms hydrogen bonds, whereas compound 2 does not Compound 2, because it is less polarizable and has weaker London dispersion forces than compound 1 Compound 2, because it forms hydrogen bonds, whereas compound 1 does not

Compound 2, because it forms hydrogen bonds, whereas compound 1 does not

Based on the information above, which of the following expressions represents the equilibrium constant, K, for the reaction represented by the equation below? (diagrams '17 #45) K = (K1)(Ka)(Kw) K = (K1)(Ka)/(Kw) K = (K1)/((Ka)(K2)) K = (K1)(Kw)/(Ka)

K = (K1)(Kw)/(Ka)

Based on the diagram above, which of the following best helps to explain why MgO(s) is not able to conduct electricity, but MgO(l) is a good conductor of electricity? (diagram '17 #8 MgO(s) does not contain free electrons, but MgO(l) contains free electrons that can flow MgO(s) contains no water, but MgO(l) contains water that can conduct electricity MgO(s) consists of separate Mg ions and O ions, but MgO(l) contains MgO molecules that can conduct electricity MgO(s) consists of separate Mg ions and O ions held in a fixed lattice, but in MgO(l) the ions are free to move and conduct electricity

MgO(s) consists of separate Mg ions and O ions held in a fixed lattice, but in MgO(l) the ions are free to move and conduct electricity

Acid dissociation constants of two acids are listed in the table above. A 20mL sample of a .1M solution of each acid is titrated to the equivalence point with 20 mL of .1M NaOH. Which of the following is a true statement about the pH of the solutions at the equivalence point? (diagram '17 #60) Solution 1 has a higher pH at the equivalence point because CH3CO2H is the stronger acid Solution 1 has a higher pH at the equivalence point because CH3CO2H has a stronger conjugate base Solution 1 has a lower pH at the equivalence point because CH3CO2H is the stronger acid Solution 1 has a lower pH at the equivalence point because CH3CO2H has a stronger conjugate base

Solution 1 has a higher pH at the equivalence point because CH3CO2H has a stronger conjugate base

The table above provides some helpful information about two types of steel, both of which are alloys of iron and carbon. Which of the following best helps explain why high carbon steel is more rigid than low carbon steel? (diagram '17 #27) Elemental carbon is harder than elemental iron The additional carbon atoms within the alloy make the high carbon and steel less dense The additional carbon atoms within the alloy increase the thermal conductivity of the high carbon steel The additional carbon atoms within the alloy make it more difficult for the iron atoms to slide past one another

The additional carbon atoms within the alloy make it more difficult for the iron atoms to slide past one another

For the system represted above, O2 and O3 initially are .15mol/L and 2.5 mol/L respectively. Which of the following best predicts what will occur as the system approaches equilibrium at 570K? (diagram '17 #41) The amount of O3 will increase because Q < Kc The amount of O3 will decrease because Q < Kc The amount of O3 will increase because Q > Kc The amount of O3 will decrease because Q > Kc

The amount of O3 will decrease because Q > Kc

Which of the following correctly compares periodic properties of two elements and provides an accurate explanation for that difference? The first ionization energy of Al is greater than that of B because Al has a larger nuclear charge than B does The first ionization energy of F is greater than that of O because O has a higher electronegativity than F has The atomic radius of Ca is larger than that of Mg because the valence electrons in Mg experience more shielding than the valence electrons in Ca do The atomic radius of Cl is smaller than that of S because Cl has a larger nuclear charge than S does

The atomic radius of Cl is smaller than that of S because Cl has a larger nuclear charge than S does

2H2 + O2 --> 2H2O When H2 and O2 are mixed together in a rigid reaction vessel at 25C, no reaction occurs. When the mixture is sparked, however, the gasses react vigorously according to the reaction above, releasing heat. Which of the following statements correctly explains why the spark is needed for the reaction to occur when the gases are originally at 25C? The reaction is not thermodynamically favorable at 25C H for the reaction has a large positive value at 25C S for the reaction has a large negative value at 25C The reaction has a large activation energy at 25C

The reaction has a large activation energy at 25C

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? (diagram '17 #59) Benzene is nonpolar, therefore there are no forces between water and benzene The H atoms in benzene form hydrogen bonds with the O atoms in water Benzene is hydrophobic, therefore there is a net repulsion between water and benzene There are dipole-induced dipole and London dispersion interactions between water and benzene

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

The ionization energy of an unknown element, X, are listed in the table to the left. Which of the following is the most likely empirical formula of a compound formed from element X and phosphorus, P? (diagram '18 #9) XP X3P X3P2 X3P4

X3P2

Three saturated solutions (X, Y, and Z) are prepared at 25C. Based on the information in the table above, which of the following lists the solutions in order of increasing [Ag+]? (diagram '17 #39) X<Z<Y Y<X<Z Z<Y<X Z<X<Y

Z<X<Y

The mass spectrum of an average sample of a pure element is shown in the figure above. Which of the following is the identity of the element? (diagram '17 #1) Y Zr Nb Th

Zr