Chemistry 132 Final Exam 1

Nitrogen dioxide decomposes at 300°C via a second-order process to produce nitrogen monoxide and oxygen according to the following chemical equation. 2 NO2(g) --> 2 NO(g) + O2(g). A sample of NO2(g) is initially placed in a 2.50-L reaction vessel at 300°C. If the half-life and the rate constant at 300°C are 11 seconds and 0.54 M-1 s-1, respectively, how many moles of NO2 were in the original sample? Question options: A)0.17 mol B)0.42 mol C)5.9 mol D)15 mol

.42 mol

At a certain temperature the equilibrium constant, Kc, equals 0.11 for the reaction: 2 ICl(g) ⇌ I2(g) + Cl2(g). What is the equilibrium concentration of ICl if 0.75 mol of I2 and 0.75 mol of Cl2 are initially mixed in a 2.0-L flask? Question options: A)0.45 M B)0.28 M C)0.23 M D)0.56

.45M

The decomposition of ammonia is: 2 NH3(g) ⇌ N2(g) + 3 H2(g). If the partial pressure of ammonia is 1.6 × 10-3 atm and the partial pressures of N2 and H2 are each 0.25 atm at equilibrium, what is the value for Kc at 400°C for the forward reaction? A) 0.50 B) 1.4 C) 4.6 × 106 D) 1.5 × 103

.50

The equilibrium constant Kc for the reaction HF(aq) + H2O(l) ⇌ H3O+(aq) +F-(aq) is 3.5 × 10-4. What is the equilibrium concentration of H3O+ if the initial concentration of HF is 1.0 M? A) 1.0 M B) 3.5 × 10-2 M C) 1.9 × 10-2 M D) 1.9 × 10-4 M

1.9x10^-2 M

How many grams of sucrose, C12H22O11 (MW = 342.300 g/mol), must be added to 500. g of water (MW = 18.015 g/mol) at 100°C to change the vapor pressure to 752 mm Hg? Question options: A)0.295 g B)10.6 g C)101 g D)5.32 g

101g

Diffraction of X-rays with λλ = 148.1 pm occurred at an angle of 35.5o from the surface of crystalline madeupium. What is the minimum spacing, in pm, between the atomic layers in this crystal?

127.5pm

Unobtanium is a non-electrolyte that is soluble in water. What is the osmotic pressure, in atm, of a 1.33 molar solution of unobtanium at 40.7 oC? Please express your answer to the appropriate number of significant figures. (R = 0.082057 L·atmmol·KL·atmmol·K)

34.3 atm

The following reaction is first order: C2H6 --> 2 CH3. If the rate constant is equal to 5.5 × 10-4 s-1 at 1000 K, how long will it take for 0.35 mol of C2H6 in a 1.00 L container to decrease to 0.10 mol in the same container? A) 7.6 min B) 38 min C) 106 min D) 131 min

38 min

NaCl crystallizes in a cubic unit cell with Cl- ions on each corner and each face. How many Na+ and Cl- ions are in each unit cell of NaCl? Question options: A)2 Na+ ions and 2 Cl- ions B)4 Na+ ions and 4 Cl- ions C)1 Na+ ion and 1 Cl- ion D)8 Na+ ions and 8 Cl- ions

4 Na+ ions and 4 Cl- ions

An aqueous reaction occurs by a two-step mechanism, shown below. Step 1: A2X2 + Y --> A2X + XY Step 2: A2X2 + XY --> A2X + X2 + Y In this reaction the intermediate is ________, and the catalyst is ________. Question options: A)A2X; XY B)XY; Y C)Y; A2X D)XY; A2X

XY;Y

What will the final molarity of a solution formed by the dilution of 125.9 ml of a 6.85 molar solution to a volume of 595.7 ml be? Please express your answer to the appropriate number of significant figures

1.44M

The solubility of gaseous zarclunium in madeupium is 0.427 moles per liter at a zarclunium pressure of 151 torr. Using Henry's Law, determine the solubility of zarclunium, in moles per liter, at a zarclunium pressure of 513 torr.

1.45

A plot of 1/[BrO-] vs time is linear for the reaction: 3 BrO-(aq) --> BrO3-(aq) + 2 Br-(aq) What is the order of the reaction with respect to the hypobromite ion, BrO-? Question options: A)0 B)1 C)2 D)3

2

Which equilibrium below is homogeneous? Question options: A)2 H2O2(l) ⇌ 2 H2O(l) + O2(g) B)NH4NO3(s) ⇌ N2O(g) + 2 H2O(g) C)2 CO(g) + O2(g) ⇌ 2 CO2(g) D)BaSO4(s) ⇌ Ba2+(aq) + SO42-(aq)

2 CO(g) + O2(g) ⇌ 2 CO2(g)

If Kc = 2.0 x 1033 at 25°C, for the following reaction: H2(g) + Cl2(g) ⇌ 2 HCl(g), then find Kp at the same temperature. Question options: A)8.2 × 10^31 B)2.0 × 10^33 C)9.7 × 10^32 D)4.9 × 10^34

2.0x10^33

the aquation of tris(1, 10-phenanthroline)iron(II) in acid solution takes place according to the equation: Fe(phen)32+ + 3 H3O+ + 3 H2O --> Fe(H2O)62+ + 3 phenH+. If the activation energy, Ea, is 126 kJ/mol and the rate constant at 30°C is 9.8 × 10-3 min-1, what is the rate constant at 50°C? (R = 8.3145 J/mol K) Question options: A)4.4 × 10-4 min-1 B)4.6 × 100 min-1 C)2.2 × 10-1 min-1 D)2.3 × 103 min-1

2.2 × 10-1 min-1

If Kc equals 0.11 at 25°C for the reaction: N2O4(g) ⇌ 2 NO2(g), what is Kc for the reaction: NO2(g) ⇌ 1/2 N2O4(g)? Question options: A)4.5 B)9.1 C)3.0 D)0.33

3.0

For the reaction: N2(g) + 2 O2(g) ⇌ 2 NO2(g), Kc = 8.3 × 10-10 at 25°C. What is the concentration of N2 gas at equilibrium when the concentration of NO2 is five times the concentration of O2 gas? Question options: A)1.7 × 10-10 M B)3.3 × 10-11 M C)3.0 × 10^10 M D)6.0 × 10^9 M

3.0 × 10^10 M

In aqueous solution, hypobromite ion, BrO-, reacts to produce bromate ion, BrO3-, and bromide ion, Br-, according to the following chemical equation. A plot of 1/[BrO-] vs. time is linear and the slope is equal to 0.056 M-1s-1. If the initial concentration of BrO- is 0.80 M, how long will it take one-half of the BrO- ion to react? A) 12 s B) 22 s C) 4.5 × 10-2 s

22s

Madeupium has a vapor pressure of 152.9 torr at 271.5 Kelvins and 906.5 torr at 324.9 Kelvins. Calculate the heat of vaporization for madeupium in kJ/mol.

24.4 kj/mol h(vap)= ((ln906.5-ln152.9)(8.3145))/((1/271.5)-(1/324.9))

The reaction for the decomposition of dinitrogen monoxide gas to form oxygen radicals is: . If the rate constant is 3.04 × 10-2 s-1 and the frequency factor is 8.00 × 1011 s-1, what is the activation energy for the first-order reaction at 700°C? k=Ae*( -Ea/RT) R=8.3145 Question options: A)38.2 kJ/mol B)250 kJ/mol C)180 kJ/mol D)0.262 kJ/mol

250 kj/mol

Silver crystallizes in a face-centered cubic structure. What is the edge length of the unit cell if the atomic radius of silver is 144 pm? Question options: A)407 pm B)204 pm C)288 pm D)333 pm

407 pm

How many H- ions are around each Na+ ion in NaH, which has a cubic unit cell with H- ions on each corner and each face? The Na+ ions do not occupy tetrahedral coordination sites in this structure. Question options: A)1 B)4 C)6 D)8

6

The following pictures represent the equilibrium state for four different reactions of the type A atoms are unshaded. X atoms are shaded.Which reaction has the smallest equilibrium constant? A) A2 + B2 ⇌ 2 AB B) A2 + C2 ⇌ 2 AC C) A2 + D2 ⇌ 2 AD D) A2 + E2 ⇌ 2 AE

A2 + D2 ⇌ 2 AD

The normal boiling point occurs when the Question options: A)intermolecular forces within the liquid phase are broken. B)temperature of the pure liquid equals the external temperature. C)vapor pressure of a pure liquid equals an external pressure of one atmosphere. D)vapor pressure of the liquid equals the external pressure.

C)vapor pressure of a pure liquid equals an external pressure of one atmosphere.

Which of the following is not an allotrope of carbon? Question options: A)fullerene B)graphite C)diamond D)coal

Coal

The following diagram shows a close-up view of the vapor pressure curves for two pure liquids and two different solutions composed of these two liquids. Which curves represent pure liquids and which curves represent the solutions? Question options: A)Curves (a) and (b) are the pure liquids and curves (c) and (d) are the solutions. B)Curves (c) and (d) are the pure liquids and curves (a) and (b) are the solutions. C)Curves (a) and (d) are the pure liquids and curves (b) and (c) are the solutions. D)Curves (a) and (c) are the pure liquids and curves (b) and (d) are the solutions.

Curves (c) and (d) are the pure liquids and curves (a) and (b) are the solutions.

In general, as the temperature increases, the solubility of gases in water ________ and the solubility of most solids in water ________. Question options: A)decreases, decreases B)increases, decreases C)increases, increases D)decreases, increases

Decreases, Increases

The half-life of the reaction shown below is found not to depend on the concentration of H2O2(aq). 2 H2O2(aq) --> 2 H2O(l) + O2(g) What is the order of this reaction? Question options: A)zero B)first C)second D)third E)Fourth

First

A mechanism for a naturally occurring reaction that destroys ozone is: Step 1: O3(g) + HO(g) --> HO2(g) + O2(g) Step 2: HO2(g) + O(g) --> HO(g) + O2(g) Which species is a catalyst? Question options: A)O3 B)HO C)O D)HO2

HO

Shown below is a concentration vs. time plot for the reaction A ⇌ B. For this reaction the value of the equilibrium constant is Question options: A)Kc = 0. B)Kc = 1. C)Kc < 1. D)Kc > 1.

Kc < 1.

if the units for rate are M s-1, what are the units for the rate constant, k, for a zeroth-order reaction? Question options: A)M-1 s-1 B)s-1 C)M s-1 D)M-1

M s-1

Which has the smallest intermolecular forces? Question options: A)CO B)N2 C)HCl D)CH3F

N2

Choose the most electronegative element: Question options: A)N B)Br C)C D)Cl E)O

O

Which of the following compounds forms a covalent network solid? Question options: A) SnCl4 B) SiO2 C) NO2 D) C8H18

SiO2

The dissolution of calcium hydroxide is exothermic. Ca(OH)2(s) ⇌ Ca2+(aq) + 2 OH-(aq) What happens when the solution of Ca(OH)2 is heated? Question options: A)The amount of Ca(OH)2(s) remains unchanged. B)The amount of Ca(OH)2(s) decreases. C)The amount of Ca(OH)2(s) increases. D)The Ca(OH)2(s) completely dissolves.

The amount of Ca(OH)2(s) increases.

Which one of the following statements does not describe the equilibrium state? Question options: A)Equilibrium is dynamic and there is no net conversion to reactants and products. B)The rate of the forward reaction is equal to the rate of the reverse reaction. C)The concentration of the reactants and products reach a constant level. D)The concentration of the reactants is equal to the concentration of the products.

The concentration of the reactants is equal to the concentration of the products.

Which of the following statements is true for a supersaturated solution? Question options: A)A supersaturated solution is more than 50% solute by mass. B)The solution is stable and the solute will not precipitate. C)The solute in the solution is at equilibrium with the undissolved solute. D)The solution contains more than the equilibrium amount of solute.

The solution contains more than the equilibrium amount of solute.

In which case should CO2(g) be more soluble in water? Question options: A)The total pressure is 5 atm and the partial pressure of CO2 is 1 atm. B)The total pressure is 3 atm and the partial pressure of CO2 is 2 atm. C)The total pressure is 1 atm and the partial pressure of CO2 is 0.5 atm. D)The total pressure is 1 atm and the partial pressure of CO2 is 0.03 atm.

The total pressure is 3 atm and the partial pressure of CO2 is 2 atm.

The structure of a solid can be determined by the diffraction of radiation in which region of the electromagnetic radiation spectrum? Question options: A)microwave B)visible C)infrared D)X-ray

X-ray

A saturated solution is defined as Question options: A)a solution that is in equilibrium with both pure solvent and undissolved B)a concentrated solution. C)a solution that is in equilibrium with undissolved solute. D)a solution that is in equilibrium with pure solvent

a solution than is in equilibrium with undissolved solute.

O2 and O3 are ________ of oxygen. Question options: A)stereomers B)isotopes C)allotropes D)isomers

allotropes

in the drawing of acetaldehyde, CH3CHO, the largest partial positive charge (δ+) occurs on Question options: A)atom (a). B)atom (b). C)atom (c). D)atom (d).

atom b

The decomposition of hydrogen peroxide is given by the following reaction: 2 H2O2(aq) --> 2 H2O(l) + O2(g) In the presence of KI the reaction is thought to occur by the following mechanism: Step 1: H2O2 + I- --> H2O + IO- Step 2: IO- + H2O2 --> H2O + O2 + I- What is the role of I- in this mechanism? A) catalyst B) transition state C) frequency factor D) intermediate

catalyst

The decomposition of hydrogen peroxide is given by the following reaction: 2 H2O2(aq) --> 2 H2O(l) + O2(g) In the presence of KI the reaction is thought to occur by the following mechanism: Step 1: H2O2 + I- --> H2O + IO- Step 2: IO- + H2O2 --> H2O + O2 + I- What is the role of I- in this mechanism? Question options: A)catalyst B)transition state C)frequency factor D)intermediate

catalyst

One reason ionic compounds do not dissolve well in nonpolar solvents is that Question options: A)not all cations and anions have the same magnitude of charge and therefore do not form neutral ion pairs. B)ion-dipole interactions are too large for effective solvation to occur. C)ion-solvent interactions are not strong enough to solvate the ions in solution. D)there are no forces of attraction between ions and nonpolar molecules.

ion-solvent interactions are not strong enough to solvate the ions in solution.

Consider the interconversion of A molecules (shaded spheres) and B molecules (unshaded spheres) according to the reaction A ⇌ B. Each of the following series of pictures represents a separate experiment in which time increases from left to right.What is the value of the equilibrium constant Kc for the reaction A ⇌ B? A) 2Kc = 27 B) Kc = 12 C) Kc = 0.33 D) Kc = 3.0

kc=3.0

Picture (1) represents an equilibrium mixture of solid CaCO3, solid CaO, and gaseous CO2, obtained as a result of the endothermic decomposition of CaCO3. Which picture (2)-(4) represents the equilibrium mixture at lower temperature? Question options: A)picture (2) B)picture (3) C)picture (4) D)all of the above

picture (3)

The change in the Gibbs free energy for dissolving more solute in a supersaturated solution is Question options: A)positive at low temperatures and negative at high temperatures. B)zero. C)positive. D)negative.

positive

Consider a reaction that occurs by the following one-step mechanism: A2 + B2 --> 2 AB The potential energy profile for this reaction is shown below. What is the species present at reaction stage 1? Question options: A)a reactant B)a transition state C)an intermediate D)a product

reactant

Which of the following mixtures have components which can be separated by filtration? Question options: A)colloids B)solutions C)suspensions D)all of the above

suspensions

For a liquid solution made by dissolving a solid or a gas in a liquid, the A) solute is the component present in the greatest amount. B) solvent is the component present in the greatest amount. C) liquid is the solute. D) liquid is the solvent.

the liquid is the solvent

The decomposition of ammonia to nitrogen and hydrogen on a tungsten filament at 800°C is independent of the concentration of ammonia at high pressures of ammonia. What is the order of the reaction with respect to ammonia? Question options: A)zero B)first C)second D)third

zero