AP Chemistry MCM

2.0 M

2 A(g) + B(g) \longrightarrow⟶ 2 C(g) Rate = k [A][B] At the beginning of one trial of this reaction, [A] = 3.0 M and [B] = 1.0 M. The observed rate for the formation of C is 0.36 mol L-1 sec-1. Determine the [A] when [B] drops to 0.50 M. 0.5 M 2.0 M 1.0 M 1.5 M

.12

2 A(g) + B(g) \longrightarrow⟶ 2 C(g) Rate = k [A][B] At the beginning of one trial of this reaction, [A] = 3.0 M and [B] = 1.0 M. The observed rate for the formation of C is 0.36 mol L-1 sec-1. The numerical value of k, the rate constant, is closest to 108 0.040 0.12 6.0

L mol-1 sec-1

2 A(g) + B(g) \longrightarrow⟶ 2 C(g) Rate = k [A][B] At the beginning of one trial of this reaction, [A] = 3.0 M and [B] = 1.0 M. The observed rate for the formation of C is 0.36 mol L-1 sec-1. What are the units for k, the rate constant? mol-1 L-1 sec mol L-1 sec-1 mol-1 L sec-1 L mol-1 sec-1

The rate at which [C] forms is equal to the rate at which [A] decreases.

2 A(g) + B(g) \longrightarrow⟶ 2 C(g) Rate = k [A][B] At the beginning of one trial of this reaction, [A] = 3.0 M and [B] = 1.0 M. The observed rate for the formation of C is 0.36 mol L-1 sec-1. Which statement below describes how the rate for this trial, at constant temperature, changes as [B] approaches 0.5 M? The rate decreases because the activation energy decreases. The rate remains the same because the rate constant remains the same. The rate at which [C] forms is equal to the rate at which [A] decreases. The rate remains the same because the temperature remains the same

HOCl (Ka = 2.0 x 10-8)

A 0.50 M solution of an unknown acid has a pH = 4.0. Of the following, which is the acid in the solution? HOCl (Ka = 2.0 x 10-8) HBr (strong acid) HF (Ka = 6.8 x 10-4) C6H5OH (Ka = 1.0 x 10-10)

[R] = [Z] > Q

A 1.0 mol sample of X(g) and a 1.0 mol sample of Q(g) are introduced into an evacuated, rigid 10.0 L container and allowed to reach equilibrium at 50ºC according to the equation above. At equilibrium, which of the following is true about the concentrations of the gases? X(g) + 2 Q(g) --> R(g) + Z(g) Kc = 1.3 x 105 at 50ºC [R] = ½ [Q] [X] = [Q] = [R] = [Z] [Q] = ½ [X] [R] = [Z] > Q

1.5 x 10-5

A 20.0 mL sample of a weak acid, HX is titrated to the end point and requires 50.0 mL of a 0.050 M KOH solution. After the addition of the first 30.0 mL of KOH, the pH of the solution is 5.00. What is the dissociation constant, Ka, for the weak acid? 3.0 x 10-6 2.0 x 10-6 6.7 x 10-6 1.5 x 10-5

30ºC

A 30. mL sample of distilled water at 10ºC is added to a 50. mL sample of the same water at 50ºC in a coffee-cup calorimeter. The final temperature of the mixture is closest to 30ºC 10ºC 20ºC 60ºC

More N2O4(g) will form and the pressure in the flask will decrease.

A flask is charged with 3.00 atm of dinitrogen tetroxide gas and 2.00 atm of nitrogen dioxide gas at 25ºC and allowed to reach equilibrium. N2O4(g) --> 2 NO2(g) Kp = 0.316 Which of the following occurs in the flask immediately upon mixing? More NO2(g) will form and the pressure in the flask will increase. More NO2(g will form and the pressure in the flask will remain constant. More N2O4(g) will form and the pressure in the flask will decrease. More N2O4(g) will form and the pressure in the flask will remain constant.

The rate of the decomposition of N2O4(g) is equal to the rate of formation of NO2(g).

A flask is charged with 3.00 atm of dinitrogen tetroxide gas and 2.00 atm of nitrogen dioxide gas at 25ºC and allowed to reach equilibrium. N2O4(g)-->2 NO2(g) Kp = 0.316 Which of the following best describes the system within the flask once equilibrium has been established? The rate of the decomposition of N2O4(g) is equal to the rate of formation of NO2(g). The partial pressure of N2O4(g) is equal to the partial pressure of NO2(g). The rate of the decomposition of N2O4(g) is greater than the rate of formation of NO2(g). The rate of the decomposition of N2O4(g) is less than the rate of formation of NO2(g).

0.025 mol

A precipitation reaction is caused by mixing 100. mL of 0.25 M K2Cr2O7 solution with 100. mL of 0.25 M Pb(NO3)2 solution. When the precipitate forms, it is filtered from the mixture. How many moles of solid product are formed? 0.25 mol 0.010 mol 0.025 mol 0.050 mol

0.25 M

A precipitation reaction is caused by mixing 100. mL of 0.25 M K2Cr2O7 solution with 100. mL of 0.25 M Pb(NO3)2 solution. When the precipitate forms, it is filtered from the mixture. What is the concentration of nitrate anion in the reaction mixture after filtration? 0.50 M 0.10 M 0.0 M 0.25 M

K+ is halved, NO3- halved

A precipitation reaction is caused by mixing 100. mL of 0.25 M K2Cr2O7 solution with 100. mL of 0.25 M Pb(NO3)2 solution. When the precipitate forms, it is filtered from the mixture. Which describes the changes in concentration of the spectator ions K+ and NO3- in the reaction mixture as the reaction occurs? K+ is doubled, NO3- halved Neither is affected Both are doubled K+ is halved, NO3- halved

Delta H is positive and Delta S is negative

A reaction is non-spontaneous at any temperature when Delta H is positive and Delta S is positive Delta H is positive and Delta S is negative Delta H is negative and Delta S is negative Delta H is negative and Delta S is positive

PO4^3-

A solution is prepared by mixing 50 mL of 1 M NaH2PO4 with 50 mL of 1 M Na2HPO4. On the basis of the information below, which of the following species is present in the solution at the lowest concentration? H3PO4(aq) \Longleftrightarrow⇔ H+(aq) + H2PO4-(aq) Ka1 = 7.2 x 10-3 H2PO4-(aq) \Longleftrightarrow⇔ H+(aq) + HPO42-(aq) Ka2 = 6.3 x 10-8 HPO42-(aq) \Longleftrightarrow⇔ H+(aq) + PO43-(aq) Ka3 = 4.5 x 10-13 Na^+ PO4^3- H2PO4^- HPO4^2-

0.625 M

A student is asked to determine the molarity of a strong base by titrating it with 0.250 M solution of H2SO4. The students is instructed to pipet a 20.0 mL portion of the strong base solution into a conical flask, to add two drops of an indicator that changes at pH = 7, and to dispense the standard H2SO4 solution from a buret until the solution undergoes a permanent color change. The initial buret reading is 5.00 mL and the final reading is 30.00 mL at the equivalence point. What is the [OH-] in the strong base solution? 0.313 M 0.750 M 0.375 M 0.625 M

Using a buret with a tip filled with air rather than the H2SO4 solution

A student is asked to determine the molarity of a strong base by titrating it with 0.250 M solution of H2SO4. The students is instructed to pipet a 20.0 mL portion of the strong base solution into a conical flask, to add two drops of an indicator that changes at pH = 7, and to dispense the standard H2SO4 solution from a buret until the solution undergoes a permanent color change. The initial buret reading is 5.00 mL and the final reading is 30.00 mL at the equivalence point. Which procedural error will result in a strong base molarity that is too high? Using 4 drops of indicator rather than the recommended 2 drops Using a buret with a tip filled with air rather than the H2SO4 solution Using an indicator that changes at pH = 5 rather than at pH = 7 Using a conical flask that contains several drops of H2O

The student failed to rinse the buret with KMnO4¬ solution after rinsing it with distilled water.

A student is doing a titration using potassium permanganate solution, KMnO4, to determine the amount of H2O2 in a sample. The balanced equation for the reaction in the titration is given below: 2 MnO4-(aq) + 6 H+(aq) + 5 H2O2(aq) -->ž 2 Mn2+(aq) + 8 H2O(l) + 5 O2(g) A student calculates an amount of moles of H2O2 that is larger than the actual value. Which of the following errors could correctly explain the larger value? The student failed to wear goggles. The student did not swirl the flask appropriately and therefore stopped short of the endpoint. The student failed to rinse the buret with KMnO4¬ solution after rinsing it with distilled water. The student added an extra 15 mL of distilled water to the H2O2 solution.

The pipet was not rinsed with HCl solution before filling

A student pipettes 25.00 mL samples of HCl solution into separate Erlenmeyer flasks, dilutes the acid with 20 mL of distilled water, and adds 3 drops of phenolphthalein to each flask. The solutions are titrated with NaOH from a buret until a pale pink color persists. The following data are recorded. Volume of NaOH solution added Trial #1 32.25 mL Trial #2 33.50 mL Trial #3 33.49 mL Trial #4 33.51 mL Which statement below is the most probable explanation for the student's results? The pipet was not rinsed with HCl solution before filling A different amount of water was added to the first flask The buret was not rinsed with NaOH solution before filling The student added too little phenolphthalein to the first solution

one-quarter as strong

According to Coulomb's Law, how does the force between a hydrogen nucleus and an electron in the n =2 level compare with that for one in the n = 1 level if the distance between the nucleus and the n = 2 level is twice as great as that between the nucleus and the n = 1 level? one-quarter as strong four times as strong one-half as strong twice as strong

0.50 J/(g·ºC)

Addition of 50. J to a 10.0-g sample of a metal will cause the temperature of a metal to rise from 25ºC to 35ºC. The specific heat of the metal is closest to 0.0005, .50, 2.5, 4.2

the number of molecules of A decreases.

All of the following apply to the reaction 2 C(s) \longrightarrow⟶ A(g) + 2 B(g) as it carried out in a sealed rigid container at constant temperature EXCEPT the rate of the reaction decreases. the number of molecules of A decreases. the entropy of the system increases. the total pressure increases.

number of core electrons

All of the following increase from left to right across the second period of the periodic table (Na - Ar) EXCEPT effective nuclear charge number of core electrons number of valence electrons atomic number

two thirds the number of moles of hydrogen

Ammonia forms when hydrogen gas reacts with nitrogen gas according to the equation below. If equal moles of nitrogen and hydrogen are combined, the maximum number of moles of ammonia that could be formed will be equal to: two thirds the number of moles of hydrogen the number of moles of hydrogen the number of moles of nitrogen twice the number of moles of nitrogen

N2O5

Assuming an equal mass of nitrogen in each compound, which oxide of nitrogen contains the greatest number of moles of oxygen atoms? NO N2O5 NO2 N2O3

K = [NH3]^2 [CO2]

At elevated temperatures ammonium carbamate, NH2COONH4, is in equilibrium with NH3 and CO2 according to the equation: NH2COONH4(s) --> 2 NH3(g) + CO2(g) What is the equilibrium expression for this reaction? K = 2[NH3] [CO2] / [NH2COONH4] K = 2[NH3] [CO2] K = [NH3]^2 [CO2] K = [NH3]^2 [CO2] / [NH2COONH4]

Ba

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? Al Li Cl Ba

high P and low T

Based on Le Chatelier's Principle, under what conditions would the yield of CH4(g) be maximized? CO2(g) + 4 H2(g) ----> CH4(g) + 2 H2O(g) ΔHº = -165 kJ/molrxn high P and low T low P and high T high P and high T low P and low T

Ethene is more stable than ethyne and they have opposite signs for Delta S

Based on the information given in the table above, what can be concluded about the relative stability and the standard entropies of formation of these compounds at 298 K? Both compounds have the same stability and they have opposite signs for Delta S Ethene is more stable than ethyne and both have the same sign for Delta S Ethene is less stable than ethyne and both have the same sign for Delta S Ethene is more stable than ethyne and they have opposite signs for Delta S (Contains table with ethene and ethyne)

H2(g)

Beginning with 1 M each of CO2(g) and H2(g) at 25ºC, which substance will have the highest concentration in an equilibrium mixture? CO2(g) + 4 H2(g) \Longleftrightarrow⇔ CH4(g) + 2 H2O(g) K = 8.2 x 1019 at 25ºC H2O(g) CH4(g) H2(g) CO2(g)

-, -, +

Butane combusts in the atmosphere and releases heat: 2C4H10(g) + 13 O2(g) ----> 8 CO2(g) + 10 H2O(g) The signs of the values for ΔG, ΔH, and ΔS for this reaction would be -, +, + -, -, + +, -, - +, +, -

3/1

Chlorine consists of two isotopes with masses of 35 and 37. If the average atomic mass of a sample of chlorine atoms is 35.5, what is the 35Cl/37Cl ratio? 4/1 3/1 2/1 1/1

36%

Copper(II) sulfate pentahydrate, CuSO4 ·5 H2O, (molar mass 250 g/mol) can be dehydrated by repeated heating in a crucible. Which value is closest to the percentage mass of water lost from the total mass of salt in the crucible when the crucible undergoes repetitive heatings until a constant mass is reached? 36% 26% 13% 25%

pKa = 4.7 & [NaOH] = 0.10 M

Data collected during the titration of a 20.0 mL sample of a 0.10 M solution of a monoprotic acid with a solution of NaOH of unknown concentration are plotted in the graph below. Based on this data, which of the following are the approximate pKa of the acid and the concentration of the NaOH? GRAPH pKa = 9.3 & [NaOH] = 0.10 M pKa = 4.7 & [NaOH] = 0.050 M pKa = 4.7 & [NaOH] = 0.10 M pKa = 9.3 & [NaOH] = 0.050 M

nitrogen monoxide, NO

Each species below has a Lewis structure that illustrates the octet rule EXCEPT: ammonium, NH4+ nitrate, NO3- nitrogen monoxide, NO ammonia, NH3

when T > 1250 K.

For some reaction, ΔHº = + 50 kJ and ΔSº = +40 J/K. The reaction will be thermodynamically favorable in the forward direction at all temperatures. at no temperature. when T > 1250 K. when T < 1250 K.

MgO(s) + CO2(g) = MgCO3(s)

For which of the following processes will DeltaΔS be negative? PbCl2(s) = Pb2+(aq) + 2 Cl-(aq) MgO(s) + CO2(g) = MgCO3(s) CO2(aq) = CO2(g) C5H12(l) + 8 O2(g) = 5 CO2(g) + 6 H2O(g)

0.11

Gaseous ICl (0.20 mol) was added to a 2.0 L flask and allowed to decompose at a high temperature: 2 ICl(g) ---> I2(g) + Cl2(g) If the equilibrium [ICl] = 0.060, what is the value of Kc? 0.11 0.33 0.67 0.44

Rate = k[Y]^2

Graph with three trials with 4-16-4 initial rates, what is the rate law? Rate = k[Y]^2 Rate = k[X][Y] Rate = k[X]^2 Rate = k[X]^2[Y]

one

How many valence electrons are present in this atom? Ionization Energy I 496 II 4562 III 6912 IV 9544 V 13353 One Two Three Four

Positive, positive

In a commercial chemical cold pack, an inner pouch containing water is broken and the water is allowed to mix with a sample of solid ammonium nitrate. The signs of the values for ΔH and ΔS for the dissociation reaction must be, respectively Positive, negative Positive, positive Negative, positive Negative, negative

4 shared pairs

In the tetrachloromethane (carbon tetrachloride) molecule the Cl-C-Cl bond angle is 109.5º. Which distribution of electrons around the central atom provides the best explanation for this bond angle? 3 shared pairs, 1 lone pair 4 shared pairs 2 shared pairs, 2 lone pairs 1 shared pair, 3 lone pairs

2 shared pairs, 2 lone pairs

In the water molecule, the H-O-H bond angle is 105º. Which distribution of electrons around the central atom provides the best explanation for this bond angle? 4 shared pairs 2 shared pairs, 2 lone pairs 1 shared pair, 3 lone pairs 3 shared pairs, 1 lone pair

Larger delta T, larger J/reaction, no change J/g, no change kJ/mol

KNO3(s) --->ž K+(aq) + NO3-(aq) This reaction was carried out in a Styrofoam insulated calorimeter and the following data were recorded: Mass of solid KNO3 dissolved 10.1 g Mass of aqueous solution (c = 4.18 J/gºC) 100. g T initial 30.0ºC T final 21.6ºC Molar mass of KNO3 101 g/mol If the mass of KNO3 solid dissolved were doubled while all other experimental conditions were kept the same, what change would occur in delta T, J per reaction, J/g of KNO3, and kJ/mol KNO3? Larger delta T, larger J/reaction, larger J/g, no change kJ/mol Larger delta T, no change J/reaction, no change J/g, no change kJ/mol Larger delta T, larger J/reaction, no change J/g, no change kJ/mol Larger delta T, larger J/reaction, larger J/g, larger kJ/mol

KNO3(s) + 35.1 kJ --> K+(aq) + NO3-(aq)

KNO3(s) --> K+(aq) + NO3-(aq) This reaction was carried out in a Styrofoam insulated calorimeter and the following data were recorded: Mass of solid KNO3 dissolved 10.1 g Mass of aqueous solution (c = 4.18 J/gºC) 100. g T initial 30.0ºC T final 21.6ºC Molar mass of KNO3 101 g/mol Which of the following equations correctly shows the heat of solution (kJ/mol) for the dissolving of KNO3? KNO3(s) + 35.1 kJ --> K+(aq) + NO3-(aq) KNO3(s) +3.51 kJ --> K+(aq) + NO3-(aq) KNO3(s) --> K+(aq) + NO3-(aq) + 8.4 kJ KNO3(s) --> K+(aq) + NO3-(aq) + 3510 kJ

CO2(s) = CO2(g)

Of the following reactions occurring at 25ºC, which one involves the greatest increase in entropy? H2(g) + Cl2(g) = 2 HCl(g) H2O(s) = H2O(l) Pb2+(aq) + 2 Cl-(aq) = PbCl2(s) CO2(s) = CO2(g)

AgBr < AgCl < Ag2CO3

On the basis of the Ksp values below, what is the order of the solubility from least soluble to most soluble for these compounds? AgBr: Ksp = 5.4 x 10-13 Ag2CO3: Ksp = 8.0 x 10-12 AgCl: Ksp = 1.8 x 10-10 Ag2CO3 < AgBr < AgCl AgBr < Ag2CO3 < AgCl AgBr < AgCl < Ag2CO3 AgCl < Ag2CO3 < AgBr

resonance structures

The Fe(CN)6- complex ion is known to have octahedral geometry. Explanation of its bonding includes all of the following EXCEPT bond angles of 90º molecular geometry that is the same as the electron geometry expanded octet resonance structures

A mixture of 100. mL of 0.1 M HC3H5O3 and 50. mL of NaOH

The acid-dissociation constants of HC3H5O3 and CH3NH3+ are given in the table below. Which of the following mixtures is a buffer with a pH of approximately 3? HC3H5O3 CH3NH3+ Ka 8.3 x 10-4 2.3 x 10-11 A mixture of 100. mL of 0.1 M NaC3H5O3 and 100. mL of NaOH A mixture of 100. mL of 0.1 M CH3NH3Cl and 100. mL of CH3NH2 A mixture of 100. mL of 0.1 M HC3H5O3 and 50. mL of NaOH A mixture of 100. mL of 0.1 M CH3NH3Cl and 50. mL of NaOH

As the temperature increases, the pH of pure water decreases.

The auto-ionization of water is represented by the equation below. Values of pKw at various temperature are listed in the table. Based upon this information, which of the following is true? 2 H2O(l) \Longleftrightarrow&iff; H3O+(aq) + OH-(aq) Temp (ºC) PKw 0 14.9 10 14.5 20 14.2 30 13.8 40 13.5 As the temperature increases, the pH of pure water decreases. As the temperature increases, the pH of pure water increases. The dissociation of water is an exothermic process. The pH of pure water is 7.00 at any temperature.

Adding HBr(aq)

The chemical equation for a saturated aqueous solution of SrF2 is shown below. Which of the following will increase [Sr2+] by the greatest amount? SrF2(s) ----> Sr2+(aq) + 2 F-(aq) Adding NaF(aq) Evaporating the solution to one-half its original volume Adding solid NaF Adding HBr(aq)

Distilled water

The dissociation of the weak acid HF in water is represented by the equation below. Adding a 1.0 mL sample of which of the following would increase the percent ionization of HF(aq) in 10 mL of a solution of 1.0 M HF? HF(aq) + H2O(l) -->H3O+(aq) + F-(aq) 1.0 M KF Distilled water 10.0 M HF 1.0 M H2SO4

K

The elements listed all react with water to produce hydrogen gas, the respective cations, and an alkaline solution. Which element reacts most vigorously? Mg Ca Na K

C6H6O3

The empirical formula of pyrogallol is C2H2O. Its molar mass is 126 g mol-1. What is the molecular formula? C4H4O2 C2H6O3 C6H6O3 C2H2O

1/(95)^2

The equilibrium constant for the gas phase reaction: N2O5(g) ---> 2 NO2(g) + ½ O2(g) is 95 at 25ºC. What is the value of the equilibrium constant for the following reaction at 25ºC? O2(g) + 4 NO2(g) ---> 2 N2O5(g) 1/95 (95)^2 1/(95)^2 (95)^½

Initial: forward rate > reverse rate Equilibrium: forward rate = reverse rate

The equilibrium: 2 NO2(g) \Longleftrightarrow&iff; N2O4(g) has Kc = 4.7 at 100ºC. What is true about the rates of the forward (ratefor) and reverse (raterev) reactions initially and at equilibrium if an empty container is filled with just NO2? Initial: forward rate < reverse rate Equilibrium: forward rate > reverse rate Initial: forward rate > reverse rate Equilibrium: forward rate > reverse rate Initial: forward rate > reverse rate Equilibrium: forward rate = reverse rate Initial: forward rate = reverse rate Equilibrium: forward rate = reverse rate

Decreasing the pH

The exothermic dissolution of Mg(OH)2(s) in water is represented by the equation below. The Ksp of Mg(OH)2 is 1.8 x 10-11. Which of the following changes will increase the solubility of Mg(OH)2 in an aqueous solution? Mg(OH)2(s) --->; Mg2+(aq) + 2 OH-(aq) Adding NH3 to the solution Increasing the pH Decreasing the pH Adding Mg(NO3)2 to the solution

decrease in the repulsion between electrons.

The increase in ionization energies for these five electrons is best attributed to a(n) Ionization Energy I 496 II 4562 III 6912 IV 9544 V 13353 increase in the charge of the nucleus. increase in the size of the nucleus. decrease in the repulsion between electrons. decrease in the charge of the ion formed.

AgSCN > AgBr > AgCN

The molar solubilities of the following compounds (in mol/L) are: AgBr = 7.3 x 10-7 AgCN = 7.7 x 10-9 AgSCN = 1.0 x 10-6 When these compounds are arranged in order of decreasing Ksp values, what is the correct order? AgCN > AgSCN > AgBr AgBr > AgCN > AgSCN AgSCN > AgBr > AgCN AgCN > AgBr > AgSCN

4

The pH of a 0.0001 M HNO3 solution is 2 4 3 1

(32/140) x 100

The percentage of oxygen in C8H12O2 is: (32/124) x 100 (32/140) x 100 (16/140) x 100 (16/124) x 100

The attractive and repulsive forces are balanced, so the atom will maintain and average internuclear distance x.

The potential energy of a system of two atoms as a function of their internuclear distance is shown in the diagram to the below. Which of the following is true regarding the forces between the atoms when their internuclear distance in x? BIG GRAPH There is a net repulsive force pushing the atoms apart, so the atoms will move further apart. It cannot be determined whether the forces between the atoms are balanced, attractive, or repulsive, because the diagram shows only potential energy. The attractive and repulsive forces are balanced, so the atom will maintain and average internuclear distance x. There is a net attractive force pulling the atoms together, so the atoms will move closer together.

CO3^2-

The reaction represented below is observed to proceed spontaneously to the right in aqueous solution. In this system, the strongest base is HSO4-(aq) + CO32-(aq) --> SO42-(aq) + HCO3-(aq)

CO3^2-

The reaction represented below is observed to proceed spontaneously to the right in aqueous solution. In this system, the strongest base is HSO4-(aq) + CO32-(aq) \Longleftrightarrow&iff; SO42-(aq) + HCO3-(aq) HSO4^- CO3^2- HCO3^- SO4^2-

Lowering the temperature of the system

The reaction system represented below is at equilibrium. Which of the following will decrease the amount CaO(s) in the system? CaCO3(s) ---> CaO(s) + CO2(g) ΔHº = 178 kJ/molrxn Removing some CO2(g) at constant temperature Increasing the volume of the reaction vessel at constant temperature Lowering the temperature of the system Removing some CaCO3(s) at constant temperature

N2O4(g) will form NO2(g) because Q = 6.0

The reaction: 2 NO2(g) \Longleftrightarrow&iff; N2O4(g) has K = 4.7 at 100ºC. What changes will occur as a system in which [NO2] = 0.50 and [N2O4] = 1.50 approaches equilibrium? No changes will occur in [NO2] or [N2O4] because the system is at equilibrium NO2(g) will form N2O4(g) because Q = 3.0 NO2(g) will form N2O4(g) because Q = 1.5 N2O4(g) will form NO2(g) because Q = 6.0

(1/K1)^½

The reaction: 2 SO2(g) + O2(g) --> 2 SO3(g) has an equilibrium constant of K1. What is the K value for the reaction: SO3(g) --> SO2(g) + ½ O2(g)? K1^½ 1/K1 ½ K1 (1/K1)^½

lower the activation energy for the reaction.

The role of a catalyst in a chemical reaction is to lower the activation energy for the reaction. decrease the amount of reactants that must be used. supply the activation energy required for the reaction to proceed. increase the amount of products formed at equilibrium.

trigonal planar

The shape of the BF3 molecule is best described as T-shaped see-saw tetrahedral trigonal planar

linear

The shape of the BeF2 molecule is best described as bent trigonal planar linear T-shaped

T -shaped

The shape of the IF3 molecule is best described as see-saw trigonal planar T-shaped tetrahedral

trigonal planar

The shape of the SO3 molecule is best described as trigonal planar bent T-shaped linear

greater number of occupied sublevels in the lithium atom.

The spectrum of a hydrogen atom contains a total of 26 lines, and that of lithium possess approximately eight times as many. This provides evidence for the quantum mechanical model of the atom due to larger mass of the lithium atom. greater number of lithium isotopes. greater attraction between the electrons and the lithium nucleus. greater number of occupied sublevels in the lithium atom.

The energy absorbed as the bonds in the reactants is broken is less than the energy released as the bonds in the products are formed.

The synthesis of CH3OH from CO and H2 is represented by the equation below. CO + 2 H2 ---> CH3OH ΔH < 0 Which of the following statements is true about the bond energies in this reaction? The energy absorbed as the bonds in the reactants is broken is greater than the energy released as the bonds in the products are formed. The energy released as the bonds in the reactants is broken is greater than the energy absorbed as the bonds in the products are formed. The energy released as the bonds in the reactants is broken is less than the energy absorbed as the bonds in the products are formed. The energy absorbed as the bonds in the reactants is broken is less than the energy released as the bonds in the products are formed.

The pH of pure water decreases as the temperature is increased.

The value of Kw at several different temperatures in given in the table below. What conclusion can be drawn on the basis of this information? Temperature 0ºC 25ºC 45ºC Kw 1.14 x 10-15 1.00 x 10-14 5.48 x 10-14 Pure water becomes more alkaline as the temperature is increased. The ionization of water is an exothermic process. Pure water becomes more acidic as the temperature is increased. The pH of pure water decreases as the temperature is increased.

Adding a solution containing an anion that forms an insoluble salt with only one of the metal ions

To gravimetrically analyze the silver content of a piece of jewelry made from an alloy of Ag and Cu, a student dissolves a small, pre-weighed sample in HNO3(aq). Ag+(aq) and Cu2+(aq) ions form in the solution. Which of the following should be the next step in analytical process? Adding enough base solution to bring the pH up to 7.0 Centrifuging the solution to isolate the heavier ions Evaporating the solution to recover the dissolved nitrates Adding a solution containing an anion that forms an insoluble salt with only one of the metal ions

C

To maximize the yield in a certain manufacturing process, a solution of an acid with a molarity between 0.20 M and 0.30 M is required. Four 100. mL samples of acid at different molarities are titrated with a 0.20 M solution of NaOH. The amount of NaOH needed to reach the endpoint for each sample is in the data table below. Which solution is most suitable for the process? Acid Solution Volume of NaOH needed to reach end point A 40 B 75 C 115 D 200 C D B A

Five electrons are gained.

What change occurs during the reaction: MnO4- --->Mn2+? Five electrons are lost. Three electrons are lost. Five electrons are gained. Three electrons are gained.

2 x 1.5 x 22.4

What expression approximates the volume of O2 consumed, measure at STP, when 55 g of Al reacts completely with excess O2? 2 Al(s) + 3 O2(g) --> 2 Al2O3(s) 0.5 x 0.67 x 22.4 2 x 1.5 x 22.4 0.5 x 1.5 x 22.4 2 x 0.67 x 22.4

1 x 10^15 h

What is the energy of a photon (in units of h) that has a wavelength of 300 nm? (c = 3.00 x 108 m/s) 1 x 10^17 h 1 x 10^15 h 1 x 10^6 h 1 x 10^-2 h

3.0

What is the pH of a solution made by adding 200 mL of distilled water to 100 mL of 0.0030 M HNO3? (assume volume are additive) 2.0 1.0 3.0 2.7

K1^2 x K2

What is the value for the reaction: N2(g) + 2 O2(g) --> N2O4(g) in terms of K values from the reactions: ½ N2(g) + ½ O2(g) ---> NO(g) K1 2 NO(g) + O2(g) ---> N2O4(g) K2 K1^2 + K2 2 K1 x K2 K1^2 x K2 K1 + K2

18 g

What mass of water can be obtained from 4.0 g of H2 and 16 g of O2? 2 H2 + O2 ---> 2 H2O 18 g 36 g 54 g 9 g

Large positive value

What value of the equilibrium constant, K, at 25ºC corresponds to a large negative value of ΔGº? Small negative value Small positive value Large negative value Large positive value

36

When 4.00 mol of each X(g) and Y(g) are placed in a 1.00 L vessel and allowed to react at constant temperature according to the equation below, 6.00 mol of Z(g) is produced. What is the value of the equilibrium constant, Kc? X(g) + Y(g) ---> 2 Z(g) 8 16 36 6

Ag+(aq) + Cl-(aq) = AgCl(s)

Which equation best describes the net changes based upon the observation that solid silver nitrate and solid potassium chloride are soluble in water and these solutions react to form insoluble silver chloride and soluble potassium nitrate when mixed? AgNO3(s) + KCl(s) = AgCl(s) + KNO3(aq) Ag+(aq) + Cl-(aq) = AgCl(s) AgNO3(s) + KCl(s) = AgCl(s) + KNO3(s) AgNO3(aq) + KCl(aq) = AgCl(s) + KNO3(aq)

12/46 x 100

Which expression gives the mass percent of carbon in methanoic (formic) acid, HCOOH? 12/29 x 100 12/46 x 100 2/46 x 100 16/46 x 100

Both mechanism 1 and 2 are consistent with the rate law.

Which mechanism shows is true? Neither mechanism 1 nor mechanism 2 is consistent with the rate law. Only mechanism 2 is consistent with the rate law. Both mechanism 1 and 2 are consistent with the rate law. Only mechanism 1 is consistent with the rate law.

P

Which of the atoms below has the largest atomic radius? N O P S

2 M Al3+(aq) and 6 M NO3-(aq)

Which of the following best describe the particles present in a 2.0 M aqueous solution of Al(NO3)3? 2 M Al3+(aq) and 18 M NO3-(aq) 2 M Al(NO3)3(aq) 2 M Al3+(aq) and 6 M NO3-(aq) 2 M Al3+(aq) and 3 M NO3-(aq)

CH3COOH & CH3COO^-

Which of the following correct pairs an acid with its conjugate base? H2PO4^2- & PO4^3- CH3COOH & CH3COO^- H3O^+ & OH^- HClO3 & HClO2

K is greater than 1

Which of the following is correct about the equilibrium constant K if ΔG < 0? K is zero K is less than 1 K is equal to 1 K is greater than 1

1s2 2s2 2p6 3s1 3p1

Which of the following is the electron configuration of an excited atom that is likely to emit a quantum of energy? 1s2 2s2 2p6 3s2 1s2 2s2 2p6 3s2 3p5 1s2 2s2 2p6 3s2 3p1 1s2 2s2 2p6 3s1 3p1

H2

Which of the following molecules is predicted to have the smallest molecular dipole moment? HI HCl H2 HBr

lithium sulfide

Which of these alkali metal sulfides has the greatest mass percent sulfur? magnesium sulfide cesium sulfide potassium sulfide lithium sulfide

VO

Which oxide of vanadium contains the greatest mass percent of the metal? V2O3 VO2 VO V2O5

all of these

Which oxide(s) of manganese have a mass percent of the metal that is greater than 50%? MnO MnO2 Mn2O3 All of these 2 1 0

0.20 mol Br2O and 0.20 mol HBrO

Which pair of samples contains the same number of oxygen atoms in each compound? 0.20 mol Ba(OH)2 and 0.20 mol H2SO4 0.20 mol Br2O and 0.20 mol HBrO 0.10 mol Fe2O3 and 0.50 mol BaO 0.10 mol Na2O and 0.10 mol Na2SO4

volume of 1.0 M NaOH needed to reach equivalence point

Which quantity is the same for separate 25 mL portions of 1.0 M strong and weak acids? (Assume Ka of weak acid ~ 1 x 10-5) pH at equivalence point of titration with 1.0 M NaOH percent ionization initial pH volume of 1.0 M NaOH needed to reach equivalence point

SO2

Which species exhibits a bent molecular geometry? SO2 HCl PH3 CH4

Y, because the rate of disappearance will be double that of X.

X + 2Y --> XY2, initial 2 which of the reactants would be consumed more rapidly? Y, because the rate of disappearance will be double that of X. X, because the reaction is second order with respect to X. Y, because the reaction is second order with respect to Y. X, because it has a higher molar concentration.

1/X VS Time

X --> products which graph represents the rate of decomposition?