Chemistry AP Midterm

A tank contains both nitrogen and hydrogen gas. If the partial pressures are 250 mmHg and 150 mmHg respectively, what is the mole fraction of nitrogen?

0.625

How many grams of calcium nitrate, Ca(NO3)2, contains 24 grams of oxygen atoms?`

41g

A student wishes to prepare 2.00 Liters of a 0.100 M KIO3 (molecular weight 214). The proper procedure is to weigh out

42.8 grams of KIO3 and add H2O until the final homogeneous solution has a volume of 2.00 L

An excess of Mg(s) is added to 100. mL of 0.400 M HCl. At 0 °C and 1 atm pressure, what volume of of H2 gas can be obtained?

448 mL

. . . CrO2-1 + . . . OH-1 → . . . CrO4-2 + . . . H2O + . . . e-1 When the equation for the half-reaction above is balanced, what is the ratio of the coefficients

4:1

10 HI + 2 KMnO4 + 3 H2SO4 → 5 I2 + 2 MnSO4 + K2SO4 + 8 H2O According to the balanced equation above, how many moles of HI would be necessary to produce 2.5 moles of I2, starting with 4.0 moles of KMnO4 and 3.0 moles of H2SO4?

5.0

H2(g) + Br2(g) 2 HBr(g) At a certain temperature, the value of the equilibrium constant, K, for the reaction represented above is 2.0 x 105. What is the value of K for the reverse reaction at the same temperature?

5.0 x 10-6

The isomerization of cyclopropane to propylene is a first-order process with a half-life of 19 minutes at 500 °C. The time it takes for the partial pressure of cyclopropane to decrease from 1.0 atm to 0.125 atm at 500 °C is closest to

57 min.

...Ag+1 + ...AsH3 (g) + ...OH-1 → ... Ag(s) + ...H3AsO3(aq) + ...H2O When the equation above is balanced with lowest whole-number coefficients, the coefficient for OH-1 is

6

If the vapor pressure of water at a given temperature is 400. torr, how many grams of ethylene glycol, C2H6O2, must be added to 540. mL of water to reduce the vapor pressure to 300. Torr?

620 g

A sample of 3.30 grams of an ideal gas at 150.0 °C and 1.25 atmospheres pressure has a volume of 2.00 liters. What is the molar mass of the gas? The gas constant, R, is 0.0821 (L·atm/mole-1·K)

71.6 g/mole

. . . Cr2O7-2(aq) + . . . H2S(g) + . . . H+1(aq) → . . . Cr+3(aq) + . . . S(s) + . . . H2O(l) When the equation above is correctly balanced and all coefficients are reduced to lowest whole- number terms, the coefficient for H+1(aq) is

8

Rate = k[M][N]2 The rate of a certain chemical reaction between substances M and N obeys the rate law above. The Reaction is first studied with [M] and [N] each 0.0010-molar. If a new experiment is conducted with [M] and [N] each 0.0020-molar, the reaction rate will increases by a factor of

8

A measured mass of an unreactive metal was dropped into a small graduated cylinder half-filled with water. The following measurements were made. Mass of metal = 19.611 grams Volume of water before addition of metal = 12.4 mL Volume of water after addition of metal = 14.9 mL

8 g/mL

Which of the following reactions does NOT shift significantly to the right in aqueous solution?

(e) H2O + HSO4-1 → H2SO4 + OH-1

C2 H4(g) + 3 O2(g) → 2 CO2(g) + 2 H2O(g) For the reaction of ethylene represented above, ΔH is -1,323 kJ. What is the value of ΔH if the combustion produced liquid water, H2O(l), rather than water vapor H2O(g)? (ΔH for the phase change H2O(g) → H2O(l) is -44 kJ·mole-1)

-1411Kj

H2(g) + ½ O2(g) → H2O(l) ΔH° = -286 kJ 2 Na(s) + ½ O2(g) → Na2O(s) ΔH° = -414 kJ Na(s) + ½ O2(g) + ½ H2(g) → NaOH(s) ΔH° = -425 kJ Based on the information above, what is the standard enthalpy change for the following reaction? Na2O(s) + H2O(l) → 2 NaOH(s)

-150 kJ

The molar heat of combustion of ethanol (C2H5OH) is found to be -1234.7 kJ. If the heat of Formation of water vapor is -241.8 kJ/mole and the heat of formation of carbon dioxide is -393.5 kJ/mole, what is the hat of formation of ethanol?

-277.7 kJ/mole

Given the following reactions: N2(g) + O2(g) 2 NO(g) ΔH = +180.7 kJ/mole 2 NO(g) + O2(g) 2 NO2(g) ΔH = -113.1 kJ/mole Determine the change in enthalpy for the reaction below.

-293.8 kJ/mole

I2(g) + 3 Cl2(g) 2 ICl3(g) According to the data in the table below, what is the value of ΔH° for the reaction represented above? Bond Average Bond Energy (kJ/mole) I—I 149 Cl—Cl 239 I—Cl 208

-382 kJ

CH4(g) + 2 O2(g) → CO2(g) + 2 H2O(l) ΔH° = -889.1 kJ ΔH°f H2O(l) = -285.8 kJ and ΔH°f CO2(g) = -393.5 kJ What is the standard heat of formation of methane, ΔH°f CH4(g) as calculated from the data above?

-75.8 kJ/mole

When 0.10 M solution of iron(II) nitrate reacts with a 1.0 M solution of hydrogen peroxide, the products will include

. Fe+3 and H2O

Substances X and Y that were in a solution were separated in the laboratory using the technique of fractional crystallization. This fractional crystallization is possible because substances X and Y have different

. solubilities

The alkenes are compounds of carbon and hydrogen with the general formula CnH2n. If 0.561 grams of any alkene is burned in excess oxygen, what number of moles of H2O is formed?

0.0400 mole

How many moles of solid Ba(NO3)2 should be added to 300. mL of 0.20-molar Fe(NO3)3 to increase the concentration of the NO3-1 ion to 1.0-molar? (Assume that the volume of the solution remains constant.)

0.060 moles

Which of the following aqueous solutions has the highest boiling point?

0.10 M potassium sulfate

A 20.0 mL sample of 0.200-molar K2CO3 solution is added to 30.0 mL of 0.400-molar Ba(NO3)2 Solution. Barium carbonate precipitates. The concentration of barium ion, Ba+2, in solution after Reaction is

0.160 M

W(g) + X(g) → Y(g) + Z(g) Gases W and X react in a closed, rigid vessel to form gases Y and Z according to the equation above. The initial pressure of W(g) is 1.20 atm and that of X(g) is 1.60 atm. No Y(g) or Z(g) is initially present. The experiment is carried out at constant temperature. What is the partial pressure of Z(g) when the partial pressure of W(g) has decreased to 1.0 atm?

0.20 atm

Which of the following solutions has the lowest freezing point?

0.20 m MgCl2

A sample of 0.0100 mole of oxygen gas is confined at 37 °C and 0.216 atmosphere. What would be the pressure of this sample at 15 °C and the same volume?

0.201 atm

What is the mole fraction of ethanol, C2H5OH, in an aqueous solution that is 46 percent ethanol by mass? (the molar mass of ethanol is 46 g/mole; the molar mass of water is 18 g/mole)

0.25

What number of moles of O2 is needed to produce 14.2 grams of P4O10 from P? (mm of P4O10 is 284)

0.250 moles

A 40.0 mL sample of 0.25 M KOH is added to 60.0 mL of 0.15 M Ba(OH)2. What is the molar concentration of OH-1 (aq) in the resulting solution? (Assume the volumes are addititve.)

0.28 M

A 1.0 L sample of an aqueous solution contains 0.10 mole of NaCl and 0.10 mole of CaCl2. What is the minimum number of moles of AgNO3 that must be added to the solution in order to precipitate all of the Cl-1 as AgCl(s)?

0.30 mole

Commercial vinegar was titrated with NaOH solution to determine the content of acetic acid, HC2H3O2. For 20.0 mL of the vinegar, 26.7 mL of 0.600-molar NaOH solution was required. What as the concentration of acetic acid in the vinegar if no other acid was present?

0.800 M

H3AsO4 + 3 I-1 + 2 H3O+1 → H3AsO3 + I3-1 + 3 H2O

1

Ni(CO)4(l) Ni(s) + 4 CO(g) The above process is used to created pure nickel metal. Determine the volume of CO(g) produced at a temperature of 27.0 °C and a pressure of 624 torr given that 1.71 grams of Ni(CO)4(l) decomposes.

1.2 L

A solution of toluene (molar mass 92.1 g/mole) in benzene (molar mass 78.1 g/mole) is prepared. The mole fraction of toluene in the solution is 0.100. What is the molality of the solution?

1.42 m

A sample of 9.00 grams of aluminum metal is added to an excess of hydrochloric acid. The volume of hydrogen gas produced at standard temperature and pressure is

11.2 L

The volume of distilled water that should be added to 10.0 mL of 6.00 M HCl(aq) in order to prepare a 0.500 M HCl(aq) solution is approximately

110. mL

...C10H12O4S(s) + ...O2(g) → ...CO2(g) + ...SO2(g) + ...H2O(g) When the equation above is balanced and all coefficients are reduced to their lowest whole-number terms, the coefficient for O2(g) is

12

CS2(l) + 3 O2(g) CO2(g) + 2 SO2(g) What volume of O2(g) is required to react with excess CS2(l) to produce 4.0 L of CO2(g)? Assume all gases are measured at 0 °C and 1 atm.

12 L

The system shown above is at equilibrium at 28 °C. At this temperature, the vapor pressure of water is 28 millimeters of mercury. The partial pressure of O2(g) in the system is

133 mmHg

What mass of Au is produced when 0.0500 mole of Au2S3 is reduced completely with excess H2?

19.7 g

For which of the following processes would ΔS have a negative value? I. 2 Fe2O3(s) → 4 Fe(s) + 3 O2(g) II. Mg+2 + 2 OH-1 → Mg(OH)2(s) III. H2(g) + C2H4(g) → C2H6(g)

2 Fe2O3(s) → 4 Fe(s) + 3 O2(g) H2(g) + C2H4(g) → C2H6(g)

The correct name for the following is CH3CH(CH3)CH(CH3)CH2CH3

2,3-demethylpentane

mass of an empty container3.0 grams mass of container plus solid sample 25.0 grams Volume of the solid sample 11.0 cubic centimeters The data above were gathered in order to determine the density of an unknown solid. The density of the sample should be reported as

2.00 g/cm3

Assuming ideal gas behavior, what is the density of sulfur dioxide at 750 mmHg and 20. ̊C?

2.62 g/l

2 SO2(g) + O2(g) 2 SO3(g) When 0.40 mole of SO2 and 0.60 mole of O2 are placed in an evacuated 1.00-liter flask, the reaction represented above occurs. After the reactants and the product reach equilibrium and the initial temperature is restored, the flask is found to contain 0.30 mole of SO3. Based on these results, the equilibrium constant, Kc, for the reaction is

20.

2.00 grams of a diprotic acid sample are titrated against 0.500 M potassium hydroxide solution. A student finds that 40.00 mL of the potassium hydroxide solution are required to neutralize the acid sample. Determine the molar mass of the sample.

200. g/mole

. The weight of H2SO4 (molar mass 98.1 g/mole) in 50.0 mL of a 6.00-molar solution is

29.4 g

...Li3N(s) + ...H2O(l) → ...Li+1(aq) + ...OH-1(aq) + ...NH3(g) When the equation above is balanced and all coefficients reduced to lowest whole-number terms, the coefficient for OH-1(aq) is

3

NH4NO3(s) → N2O(g) + 2 H2O(g) A 0.03 mole sample of NH4NO3(s) is placed in a 1 L evacuated flask, which is then sealed and heated. The NH4NO3(s) decomposes completely according to the balanced equation above. The total pressure in the flask measured at 400 K is closest to which of the following? (The value of the gas constant, R, is 0.082 L·atm·mole-1·K-1.)

3 ATM

Questions number 36 through 39 refer to the following reactions: (a) H2SeO4(aq) + 2 Cl-1(aq) + 2 H+1 → H2SeO3(aq) + Cl2(g) + H2O(l) (b) S8(s) + 8 O2(g) → 8 SO2(g) (c) 3 Br2(aq) + 6 OH-1(aq) → 5 Br-1(aq) + BrO3-1(aq) + 3 H2O(l) (d) Ca+2(aq) + SO4-2(aq) → CaSO4(s) (e) PtCl4(s) + 2 Cl-1(aq) → PtCl6-2(aq) A reaction in which the same reactant undergoes both oxidation and reduction.

3 Br2(aq) + 6 OH-1(aq) → 5 Br-1(aq) + BrO3-1(aq) + 3 H2O(l)

...Fe(OH)2 + ... O2 + ... H2O ...Fe(OH)3 If 1 mole of O2oxidizes Fe(OH)2 according to the reaction represented above, how many moles of Fe(OH)3 can be formed?

4

Of the following reactions, which involves the largest decrease in entropy?

4 La(s) + 3 O2(g) → 2 La2O3(s)

If 87 grams of K2SO4 (molar mass 174 grams/mole) is dissolved in enough water to make 250 mL of solution, what are the concentrations of the potassium and the sulfate ions?

4.0 M 2.0 M

When 70.0 milliliters of 3.0-molar Na2CO3 is added to 30.0 milliliter of 1.0-molar NaHCO3, the Resulting concentration of Na+1 ions is

4.5 M

What volume of 0.150-molar HCl is required to neutralize 25.0 mL of 0.120-molar Ba(OH)2 ?

40.0 mL

It is suggested that SO2 (molar mass 64 g/mole), which contributes to acid rain, could be removed from a stream of waste gases by bubbling the gases through 0.25-molar KOH, thereby producing K2SO3. What is the maximum mass of SO2 that could be removed by 1,000. L of the KOH solution?

8.0 kg

When a 1.00-gram sample of limestone was dissolved in acid, 0.38 grams f CO2 was generated. If the rock contained no carbonate other than CaCO3, what was the percent of CaCO3 by mass in the limestone?

86 %

2 N2H4(g) + N2O4(g) → 3 N2(g) + 4 H2O(g) When 8.0 grams of N2H4 (32 g/mole) and 92 grams N2O4 (92 g/mole) are mixed together and react According to the equation above, what is the maximum mass of H2O that can be produced?

9.0 g

In the qualitative analysis for the presence of Pb+2, Fe+2, and Cu+2 ions in aqueous solution, which of following will allow the separation of Pb+2 from the other ions at room temperature?

Adding dilute HCl(aq) solution.

The test for the presence of Ag+1 in an unknown solution involves the treatment of the silver- ammonia complex with dilute hydrochloric acid. The appearance of a white precipitate at this point indicates the presence of silver ion in the original sample. The net ionic equation that represents this test is

Ag(NH3)2+1 + 2 H+1 + Cl-1 AgCl(s) + 2 NH4+1

A sample of a solution of an unknown was treated with dilute hydrochloric acid. The white precipitate formed was filtered and washed with hot water. A few drops of potassium iodide solution were added to the hot water filtrate and a bright yellow precipitate was formed. The white precipitate remaining on the filter paper was readily soluble in ammonia solution. What two ions could have been present in the unknown?

Ag+1(aq) and Pb+2(aq)

A white solid is observed to be insoluble in water, insoluble in excess ammonia solution, and soluble dilute HCl. Which of the following compounds could the solid be?

AgCl

Sublimation is the major process at

B-Lower Right Line

Use the following as possible answers for numbers 23 through 26. (a) CO3-2 (b) Cr2O7-2 (c) NH4+1 (d) Ba+2 (e) Al+3 Assume that you have an 'unknown" consisting of an aqueous solution of a salt that contains one of the ions listed above. Which ion must be absent on the basis of each of the following observations of the 'unknown"? No precipitate is formed when a dilute solution of H2SO4 is added to a sample of the solution.

Ba+2

Which of the following substances is LEAST soluble in water?

BaCO3

For the reaction represented above, the experimental rate law is given as follows: Rate = K[(CH3)3Cl] If some solid sodium hydroxide is added to a solution that is 0.010-molar in (CH3)3Cl and 0.10-molar in NaOH, which of the following is true? (Assume the temperature and volume remain constant.)

Both the reaction rate and K remain the same.

A hydrocarbon gas with an empirical formula CH2 has a density of 1.88 grams per liter at 0°C and 1.00 atmosphere. A possible formula for the hydrocarbon is

C3H6

A 27.0-gram sample of an unknown hydrocarbon was burned in excess oxygen to form 88.0 grams of carbon dioxide and 27.0 grams water. What is a possible molecular formula of the hydrocarbon?

C4H6

Which of the following pairs of liquids forms the solution that is most ideal (most closely follows Raoult's Law)?

C6H14(l) and C8H18(l)

Sodium chloride is LEAST soluble in which of the following liquids?

CCl4

Which of the following pairs of compounds are isomers?

CH3-CH2-CH2-CH3 and CH3-CH(CH3)-CH3

Which of the following does NOT behave as an electrolyte when it is dissolved in water?

CH3OH

For questions number 33 through 35 refer to the following gases at 0°C and 1 atm of pressure (a) Ne (b) Xe (c) O2 (d) CO (e) NO Has an average atomic or molecular speed closest to that of N2 molecules at 0 °C and 1 atm.

CO

A 2 Liter container will hold about 4 grams of which of the following gases at 0 °C and 1 atm?

CO2

Use the following as possible answers for numbers 23 through 26. (a) CO3-2 (b) Cr2O7-2 (c) NH4+1 (d) Ba+2 (e) Al+3 Assume that you have an 'unknown" consisting of an aqueous solution of a salt that contains one of the ions listed above. Which ion must be absent on the basis of each of the following observations of the 'unknown"? The solution gives no apparent reaction with dilute hydrochloric acid.

CO3-2

Questions number 36 through 39 refer to the following reactions: (a) H2SeO4(aq) + 2 Cl-1(aq) + 2 H+1 → H2SeO3(aq) + Cl2(g) + H2O(l) (b) S8(s) + 8 O2(g) → 8 SO2(g) (c) 3 Br2(aq) + 6 OH-1(aq) → 5 Br-1(aq) + BrO3-1(aq) + 3 H2O(l) (d) Ca+2(aq) + SO4-2(aq) → CaSO4(s) (e) PtCl4(s) + 2 Cl-1(aq) → PtCl6-2(aq) A precipitation reaction.

Ca+2(aq) + SO4-2(aq) → CaSO4(s)

At 25 °C, a sample of NH3 (molar mass 17 g/mole) effuses at the rate of 0.050 mole per minute. Under the same conditions, which of the following gases effuses at approximately one-half the rate?

Cl2 (molar mass 71 g/mole)

Use the following as possible answers for numbers 23 through 26. (a) CO3-2 (b) Cr2O7-2 (c) NH4+1 (d) Ba+2 (e) Al+3 Assume that you have an 'unknown" consisting of an aqueous solution of a salt that contains one of the ions listed above. Which ion must be absent on the basis of each of the following observations of the 'unknown"? The solution is colorless.

Cr2O7-2

2 H2O + 4 MnO4-1 + 3 ClO2-1 → 4 MnO2 + 3 ClO4-1 + 4 OH-1 Which species acts as an oxidizing agent in the reaction represented above?

CrO2

In which of the following compounds is he mass ratio of chromium to oxygen closest to 1.62 to 1.00?

CrO2

When an aqueous solution of NaOH is added to an aqueous solution of potassium dichromate, K2Cr2O7, the dichromate ion is converted to

CrO4-2

HCO3-1(aq) + OH-1(aq) H2O(l) + CO3-2(aq) ΔH = -41.4 kJ/mole When the reaction represented above is at equilibrium at 1 atm and 25 °C, the ratio ([〖CO〗_3^(-2)])/([〖HCO〗_3^(-1)]) can be increased by doing which of the following?

Decreasing the temperature.

PCl3(g) + Cl2(g) PCl5(g) + energy Some PCl3 and Cl2 are mixed in a container at 200 °C and the system reaches equilibrium according to the equation above. Which of the following causes an increase in the number of moles of PCl5 present at equilibrium? I. Decreasing the volume of the container. II. Raising the temperature. III. Adding a mole of He gas at constant volume.

Decreasing the volume of the container.

The molality of the glucose in a 1.0-molar glucose solution can be obtained by using which of the following?

Density of the solution.

Correct procedures for a titration include which of the following? I. Draining a pipet by touching the tip to the side of the container used for the titration. II. Rinsing the buret with distilled water just before filling it with the liquid to be titrated. III. Swirling the solution frequently during the titration.

Draining a pipet by touching the tip to the side of the container used for the titration. Swirling the solution frequently during the titration.

All of the molecules are in equilibrium between liquid and gaseous phases at

E Top Right Curve

A cube of ice is added to some hot water in a rigid, insulated container, which is then sealed. There is no heat exchange with the surroundings. What has happened to the total energy and the total entropy when the system reaches equilibrium?

Energy Entropy Remains constant Increases

Which of the following techniques is most appropriate for the recovery of solid KNO3 from an aqueous solution of KNO3?

Evaporation to dryness.

When a solution of potassium dichromate is added to an acidified solution of iron (II) sulfate, the products of the reaction are

Fe+3 , Cr+3 , and H2O

Questions number 1 and 2 refer to the following elements. A. Lithium C. Bromine E. Fluorine B. Nickel D. Uranium Is a gas in its standard state at 298 K.

Fluorine

The safest and most effective emergency procedure to treat an acid splash on skin is to do which of the following immediately?

Flush the affected area with water and then with a dilute NaHCO3 solution.

Which of the following is lower for a 1.0-molar aqueous solution of any solute than it is for pure water?

Freezing point

H H H H-C-C-C-Br H H H Which of the following structural formulas represents an isomer of the compound that has the structural formula listed above?

H H H H-c-c-c-h H Br H

Which of the following acids can be oxidized to form a stronger acid?

H2SO3

The net ionic equation for the reaction that occurs during the titration of nitrous acid with sodium hydroxide is

HNO2 + OH-1 → NO2-1 + H2O

When hafnium metal is heated in an atmosphere of chlorine gas, the product of the reaction is found to contain 62.2 percent Hf by mass and 37.4 percent Cl by mass. What is the empirical formula for this compound?

HfCl3

The addition of an oxidizing agent such as chlorine water to a clear solution of an unknown Compound results in the appearance of a brown color. When this solution is shaken with the Organic solvent methylene dichloride, the organic solvent layer turns purple. The unknown Compound probably contains

I- Thats Iodine

Which of the following species CANNOT function as an oxidizing agent?

I-1

2 NO(g) + O2(g) 2 NO2 (g) ΔH < 0 Which of the following changes alone would cause a decrease in the value of Keq for the reaction represented above?

Increasing the temperature.

Equal masses of three different ideal gases, X, Y, and Z, are mixed in a sealed rigid container. If the temperature of the system remains constant, which of the following statements about the partial pressure of gas X is correct?

It depends on the relative molecular masses of X, Y, and Z

The graph above shows the results of a study of the reaction of X with a large excess of Y to yield Z. the concentrations of X and Y were measured over a period of time. According to the results, which of the following can be concluded about the rate law for the reaction under the conditions studied?

It is first order in [X]

Questions number 40 and 41 refer to the following: (a) PbSO4 (b) CuO (c) KMnO4 (d) KCl (e) FeCl3 Is white and very soluble in water.

KCl

Questions number 40 and 41 refer to the following: (a) PbSO4 (b) CuO (c) KMnO4 (d) KCl (e) FeCl3 Is purple in aqueous solution.

KMnO4

On the basis of the solubility curves shown above, the greatest percentage of which compound can be recovered by cooling a saturated solution of that compound from 90 °C to 30 °C?

KNO3

O || CH3-C-CH2-CH3 The organic compound represented above is an example of

Ketone

The initial-rate data in the table above were obtained for the reaction represented below. What is the experimental rate law for the reaction? 2 NO(g) + O2(g) → NO2(g)

Rate = k[NO][O2]2

Questions number 1 and 2 refer to the following elements. A. Lithium C. Bromine E. Fluorine B. Nickel D. Uranium Reacts with water to form a strong base.

Lithium

A sample of 61.8 g of H3BO3, a weak acid, is dissolved in 1000 g of water to make a 1.0-molal solution. Which of the following would be the best procedure to determine the molarity of the solution? (Assume no additional information is available.)

Measurement of the total volume of the solution.

. Which of the following compounds is NOT appreciably soluble in water but is soluble in dilute hydrochloric acid?

Mg(OH)2(s)

Use the following as possible answers for numbers 20, 21, and 22. (a) F (b) S (c) Mg (d) Ar (e) Mn Forms a compound having the formula KXO4

Mn

. A 0.10 M aqueous solution of sodium sulfate is a better conductor of electricity than a 0.10 M aqueous solution of sodium chloride. Which of the following best explains this observation?

More moles of ions are present in a given volume of 0.10 M sodium sulfate than in the same volume of 0.10 M sodium chloride.

Which of the following oxides is a gas at 25 °C and 1 atm?

N2O

Use the following as possible answers for numbers 23 through 26. (a) CO3-2 (b) Cr2O7-2 (c) NH4+1 (d) Ba+2 (e) Al+3 Assume that you have an 'unknown" consisting of an aqueous solution of a salt that contains one of the ions listed above. Which ion must be absent on the basis of each of the following observations of the 'unknown"? No odor can be detected when a sample of the solution is added drop by drop to a warm solution of sodium hydroxide.

NH4+

For questions number 33 through 35 refer to the following gases at 0°C and 1 atm of pressure (a) Ne (b) Xe (c) O2 (d) CO (e) NO Has the greatest rate of effusion through a pinhole.

Ne

A yellow precipitate form when 0.5 M NaI(aq) is added to a 0.5 M solution of which of the following ions?

PB+2

Equal numbers of moles of He(g), Ar(g), and Ne(g) are placed in a glass vessel at room temperature. If the vessel has a pinhole-sized leak, which of the following will be true regarding the relative values of the partial pressures of the gases remaining in the vessel after some of the gas mixture has effused?

PHe < PNe < PAr

When 100 mL of 1.0 M Na3PO4 is mixed with 100 mL of 1.0 M AgNO3, a yellow precipitate forms and [Ag+1] becomes negligibly small. Which of the following is a correct listing of the ions remaining in solution in order of increasing concentration?

PO4-3] < [NO3-1] < [Na+1]

Under which of the following sets of conditions could the most O2(g) be dissolved in H2O(l)?

Pressure of O2(g) Temperature of Above H2O(l) (atm) of H2O(l) (°C) 5 20

Questions number 36 through 39 refer to the following reactions: (a) H2SeO4(aq) + 2 Cl-1(aq) + 2 H+1 → H2SeO3(aq) + Cl2(g) + H2O(l) (b) S8(s) + 8 O2(g) → 8 SO2(g) (c) 3 Br2(aq) + 6 OH-1(aq) → 5 Br-1(aq) + BrO3-1(aq) + 3 H2O(l) (d) Ca+2(aq) + SO4-2(aq) → CaSO4(s) (e) PtCl4(s) + 2 Cl-1(aq) → PtCl6-2(aq) A reaction that produces a coordination complex.

PtCl4(s) + 2 Cl-1(aq) → PtCl6-2(aq)

2 NO(g) + O2(g) → 2 NO2(g) A possible mechanism for the overall reaction represented above is the following:

Rate = K[NO]2

Step 1. N2H2O2 N2HO2 -1 + H+1 (fast equilibrium) Step 2. N2HO2-1 N2O + OH-1 (slow ) Step 3. H+1 + OH-1 H2O (fast) Nitramide, N2H2O2, decomposes slowly in aqueous solution. This decomposition is believed to occur according to the reaction mechanism above. The rate law for the decomposition of nitramide that is consistent with this mechanism is given by which of the following?

Rate = k([N_2 H_2 O_2])/([H^(+1)])

Which of the following is a correct statement about reaction order?

Reaction order can be determined only by experiment.

Use the following as possible answers for numbers 20, 21, and 22. (a) F (b) S (c) Mg (d) Ar (e) Mn . Forms monatomic ions with -2 charge.

S

Use the following as possible answers for numbers 20, 21, and 22. (a) F (b) S (c) Mg (d) Ar (e) Mn Forms oxides that are common air pollutants and that yield acidic solutions in water.

S

Questions number 36 through 39 refer to the following reactions: (a) H2SeO4(aq) + 2 Cl-1(aq) + 2 H+1 → H2SeO3(aq) + Cl2(g) + H2O(l) (b) S8(s) + 8 O2(g) → 8 SO2(g) (c) 3 Br2(aq) + 6 OH-1(aq) → 5 Br-1(aq) + BrO3-1(aq) + 3 H2O(l) (d) Ca+2(aq) + SO4-2(aq) → CaSO4(s) (e) PtCl4(s) + 2 Cl-1(aq) → PtCl6-2(aq) A combustion reaction.

S8(s) + 8 O2(g) → 8 SO2(g)

Which of the following gases deviates most from ideal behavior?

SO2

Relatively slow rates of chemical reaction are associated with which of the following?

Strong bonds in reactant molecules.

A hot air balloon rises. Which of the following is the best explanation for this observation?

The air density inside the balloon is less than that of the surrounding air.

A rigid metal tank contains oxygen gas. Which of the following applies to the gas in the tank when additional oxygen is added at constant temperature?

The average speed of the gas molecules remains the same.

A sample of an idial gas is cooled from 50.0 °C to 25.0°C in a sealed container of constant volume. which of the following values for the gas will decrease? I. The average molecular mass of the gas II. The average distance between the molecules III. The average speed of the molecules

The average speed of the molecules

3 Cu(s) + 8 H+1(aq) + 2 NO3-1(aq) 3 Cu+2(aq) + 2 NO(g) + 4 H2O(l) True statements about the reaction represented above include which of the following? I. Cu(s) acts as an oxidizing agent II. The oxidation state of nitrogen changes from +5 to +2 III. Hydrogen ions are oxidized to form H2O(l)

The oxidation state of nitrogen changes from +5 to +2

According to the rate law for the reaction shown in number 15, an increase in the concentration of hydronium ion has what effect on this reaction?

The rate of reaction increases.

3. Which of the following best describes the role of the spark from the spark plug in an automobile engine?

The spark supplies some of the energy of activation for the combustion reaction.

Which of the following is a graph that describes the pathway of a reaction that is endothermic and has high activation energy?

Up and ends at a higher level

A compound is heated to produce a gas whose molecular weight is to be determined. The gas is collected by displacing water in a water-filled flask inverted in a trough of water. Which of the following is necessary to calculate the molecular weight of the gas, but does NOT need to be measured during the experiment?

Vapor pressure of water

For questions number 33 through 35 refer to the following gases at 0°C and 1 atm of pressure (a) Ne (b) Xe (c) O2 (d) CO (e) NO Has the greatest density.

Xe

Samples of F2 gas and Xe gas are mixed in a container of fixed volume. The initial partial pressure of the F2 gas is 8.0 atmospheres and that of the Xe gas is 1.7 atmospheres. When all of the Xe gas reacted, forming a solid compound, the pressure of the unreacted F2 gas was 4.6 atmosheres. The temperature remained constant. What is the formula of the compound?

XeF4

4 HCl(g) + O2(g) 2 Cl2(g) + 2 H2O(g) Equal numbers of moles of HCl and O2 in a closed system are allowed to reach equilibrium as represented by the equation above. Which of the following must be true at equilibrium? I. [HCl] must be less than [Cl2] II. [O2] must be greater than [HCl] III. [Cl2] must equal [HCl]

[O2] must be greater than [HCl]

CuO(s) + H2(g) Cu(s) + H2O(g) ΔH = -2.0 kJ When the substances in the equation above are at equilibrium at pressure P and temperature T, The equilibrium can be shifted to favor the products by

decreasing temperature

A solution is made by dissolving a nonvolatile solute in a pure solvent. Compared to the pure solvent, the solution

has a higher normal boiling point

When solid ammonium chloride, NH4Cl(s), is added to water at 25 °C, it dissolves and the temperature of the solution decreases. Which of the following is true for the values of ΔH and ΔS for the dissolving process?

postive negatve

2 SO3(g) 2 SO2(g) + O2(g) After the equilibrium represented above is established, some pure O2(g) is injected into the reaction vessel at constant temperature. After equilibrium is reestablished, which of the following has a lower value compared to its value at the original equilibrium?

the amount of SO2(g) in the reaction vessel.

6. NH3(g) + 2 CH4(g) + 5/2 O2(g) H2NCH2COOH(s) + 3 H2O(l) At constant temperature, ΔH, the change in the enthalpy for the reaction above is approximately equal to

ΔE - (11/2) RT

xWhen solid NH4SCN is mixed with solid Ba(OH)2 in a closed container, the temperature drops and a gas is produced. Which of the following indicates the correct signs for ΔG, ΔH, and ΔS for the process? When solid NH4SCN is mixed with solid Ba(OH)2 in a closed container, the temperature drops and a gas is produced. Which of the following indicates the correct signs for ΔG, ΔH, and ΔS for the process?

ΔG ΔH ΔS - + +

N2(g) + 3 H2(g) 2 NH3(g) The reaction indicated above is thermodynamically spontaneous at 298 K, but becomes nonspontaneous at higher temperatures. Which of the following is true at 298 K?

ΔG, ΔH, and ΔS are all negative.

X(s) X(l) Which of the following is true for any substance undergoing the process represented above at its normal melting point?

ΔH = T∙ΔS