Chem Final Exam Review (Minus Unit 4)

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Two gases are added to a 1.00 L container: 2.0 moles of A; 4.0 moles of B. These gases react as follows: A(g) + 3 B(g) ⇔⇔ C(g) + 2 D(g) At equilibrium the container contains 0.4 moles of D. Calculate the value of the equilibrium constant for this reaction.

.00045

Nitrosyl bromide decomposes according to the chemical equation below. 2NOBr(g) ↔ 2NO(g) + Br2(g) When 0.260 atm of NOBr is sealed in a flask and allowed to reach equilibrium, 22% of the NOBr decomposes. What is the equilibrium constant, Kp, for the reaction?

.0023

What is the hydronium ion concentration of a 1.30 M benzoic acid solution?

.0090 M

If 24.7 mL of 2.0 M HCl are titrated with 1.9 M NaOH, what is the pH at 13.2 mL?

If 20.6 mL of 2.3 M HCl are titrated with 1.2 M NaOH, what is the pH at 18.9 mL?

.207

At 90 degrees C, the following equilibrium is established: H2(g) + S(s) ↔ H2S(g) Kc = 6.8 X 10-2 If 0.13 mol of hydrogen and 0.1 mol of sulfur are heated to 90 degrees C in a 1 L vessel, what will be the partial pressure of H2S at equilibrium? Give your answer with units as atm

.25 atm

What is the hydronium concentration of a 0.43 M solution of sulfuric acid?

.43

Given the equilibrium reaction PCl5 (g) ↔ PCl3 (g) + Cl2 (g) Calculate the number of moles of Cl2 produced at equilibrium when 1.00 mol of PCl5 is heated at 272.7 deg celsius in a vessel having a capacity of 10.0L. At 272.7, K = 0.044 for this dissociation. Answer:

.479

At 90 degrees C, the following equilibrium is established: H2(g) + S(s) ↔ H2S(g) Kc = 6.8 X 10-2 If 0.49 mol of hydrogen and 0.1 mol of sulfur are heated to 90 degrees C in a 1 L vessel, what will be the partial pressure of H2S at equilibrium? Give your answer with units as atm

.93

What is the hydronium concentration of a 4.0E-6 M solution of hydrochloric acid?

What is the hydronium ion concentration of a 0.487 M acetic acid solution?

0.0029 M

How many milliliters of 0.250 M KMnO4 are needed to completely react with 3.55 g of iron (II) sulfate? The reaction is: 10FeSO4(aq) + 2KMnO4(aq) + 8H2SO4(aq) → 5Fe2(SO4)3(aq) + 2MnSO4(aq) + K2SO4(aq) + 8H2O(l)

0.0187 L or 18.7 ml

dentify which of the following results in buffer solutions when equal volumes of the two solutions are mixed. Select one or more: a. 0.2 M NaOH and 0.2 M CH3COOH b. 0.2 M HCl and 0.3 M NH3 c. 0.1 M KClO4 and 0.1 M HClO4 d. 0.3 M NaCN and 0.1M HCN e. 0.1 M KNO2 and 0.1 M HNO2 f. 0.2 M NaOH and H2O g. 0.2 M HCl and 0.1 M NH3 h. 0.1 M NaOH and 0.2 M CH3COOH

0.1 M KNO2 and 0.1 M HNO2, 0.1 M NaOH and 0.2 M CH3COOH, 0.3 M NaCN and 0.1M HCN, 0.2 M HCl and 0.3 M NH3

Calculate the molarity (M) of the excess reactant remaining in solution when mixing 112.3 mL of 0.302 M Na2CO3(aq) and 74.0 mL of 0.226 M AgNO3(aq) (molar mass of Ag2CO3 = 275.8 g/mole)

0.137 M

How many moles of oxygen atoms are found in 4.00 g of O2?

0.250

How many moles of sulfuric acid are found in 24.5 g of H2SO4? Answer with 3 significant figures with no unit.

0.250

Determine the value of Kc for the following reaction A + B ↔ 2C if the equilibrium concentrations are found to be: A = 0.835 M B= 1.255 M C = 0.65 M

0.40

18.7 ml of 0.250 M KMnO4 are needed to completely react with 3.55 g of iron (II) sulfate. What is the molarity of the resulting Fe2(SO4)3 solution?

0.626 M

Which of these substances has an abundant and distinctive molecular fragment in its mass spectrum at m/z = 93 and 95?

1-bromobutane

Given the equilibrium reaction PCl5 (g) ↔ PCl3 (g) + Cl2 (g) Calculate the number of moles of Cl2 produced at equilibrium when 3.67 mol of PCl5 is heated at 273.7 deg celsius in a vessel having a capacity of 10.0L. At 273.7, K = 0.04 for this dissociation.

1.03

How many moles of nitrogen gas, N2, are there in 35.7 g of nitrogen atoms? Answer with 3 significant figures with no unit

1.28

Calculate the molarity of a solution that is prepared by adding water to 19.31 g of KF to give a final volume of 250.0 mL. Be sure to include appropriate units in your answer.

1.329 M

Calculate the molarity of a solution that is prepared by adding water to 19.31 g of KF to give a final volume of 250.0 mL. Be sure to include appropriate units in your answer.

1.33 M

The lid is tightly sealed on a rigid flask containing 2.25 L Ar at 22 °C and 0.977 atm. If the flask is heated to 140 °C, what is the pressure in the flask?

1.37 atm

Ammonia gas is synthesized according to the balanced equation below. N2(g) + 3 H2(g) → 2 NH3(g) If 1.43 L N2 react with 2.14 L H2, what is the theoretical yield (in liters) of NH3 at STP? Include units in your answer.

1.43 L

The pH of an aqueous 0.10 M basic solution is 9.09. What is the Kb of this base? Select one: a. 8.0 x 10-10 b. 1.5 x 10-9 c. 9.0 x 10-6 d. 1.6 x 10-5 e. 1.2 x 10-5

1.5 x 10-9

How many grams of FeCl3 are produced when the reaction (unbalanced) occurs with 1.0 grams Fe2S3 being consumed? (assume excess HCl) Fe2S3(s) + HCl(g) →→ FeCl3(s) + H2S(g)

1.56 g

How many grams of FeCl3 are produced when the reaction (unbalanced) occurs with 1.0 grams Fe2S3 being consumed? (assume excess HCl) Fe2S3(s) + HCl(g) →→ FeCl3(s) + H2S(g)

1.56 grams

Two gases are added to a 1.00 L container: 2.0 moles of A; 4.0 moles of B. These gases react as follows: A(g) + 3 B(g) ⇔⇔ C(g) + 2 D(g) At equilibrium the container contains 0.6 moles of D. Calculate the concentration of A at equilibrium. Include the appropriate unit and answer to 2 significant figures.

1.7 M

Krypton gives the following mass spectrum:From the mass spectrum of Krypton (atomic number = 36) shown, determine the fractional abundance (%) of the isotope with mass of 82 amu.

10%

How many moles of oxygen atoms are there in 6.02 x 1024 atoms of CO?Answer with 3 significant figures with unit

10.00 mol

Isotopic abundances are different in other parts of the universe. Suppose that on planet Krypton we find the following stable isotopes and abundances for boron: 10B (10.013 amu) 65.75% 11B (11.0009 amu) 25.55% 12B (12.014 amu) 8.70% What is the value of the average atomic mass of boron on planet Krypton in amu?

10.442

Isotopic abundances are different in other parts of the universe. Suppose that on planet Krypton we find the following stable isotopes and abundances for boron: 10B (10.013 amu) 67.75% 11B (11.009 amu) 25.55% 12B (12.014 amu) 8.7%

10.442

If 28.8 mL of 1.5 M C2H5NH2 are titrated with 0.5 M HCl, what is the pH at 11.4 mL?

11.5

How many grams of aluminum chloride can be produced from 1.30 moles of Cl2 and 2.52 moles of Al? The chemical equation is 3Cl2 + 2Al → 2AlCl3

116 g

What is the pH of a 3.5 M solution of a weak base with Kb= 0.000034?

12.04

What mass of solid NaCH3CO2 should be added to 1.1 L of 0.6 M CH3CO2H to make a buffer with a pH of 5.12? Answer with 1 decimal place. Make sure to include unit in your answer.

121.2 g

What is the hydronium ion concentration of a 3.9 M Aniline (C6H5NH2) solution?

2.5E-10 M

How many hydrogen atoms are present in 0.235 g of NH3? report your answer as programmers notation to 2 sig figs

2.5e22

Ammonia gas is synthesized according to the balanced equation below. N2(g) + 3 H2(g) → 2 NH3(g) If 2.31 L N2 react with 4.41 L H2, what is the theoretical yield (in liters) of NH3 at STP?

2.94 L

Krypton gives the following mass spectrum:From the mass spectrum of Krypton (atomic number = 36) shown, determine the fractional abundance (%) of the isotope with mass of 86 amu.

20%

What is the average mass of the atom from the given mass spectrum (There's a bar graph that shows the Y axis as Instensity % and 50% and 100% and the X axis in mass AMU have the numbers 204, 206, 207, 208)

207.2

A metal, M, forms an oxide having the formula M2O3 containing 52.92% metal by mass. Determine the atomic weight in g/mole of the metal (M). Please provide your answer in 2 decimal places.

26.98

What is the hydroxide concentration of a 0.635 M acetic acid solution?

3.0e-12 M

3.1 M

If Kc = 0.68 for this reaction 3H2(g) + N2(g) ⇔⇔ 2NH3(g) what is the value for Kc for the following reaction at the same temperature? 6NH3(g) ⇔⇔ 9H2(g) + 3N2(g

3.2

The base imidazole (Im) has a Kb of 9.8 x 10-8. Calculate the ratio of imidazole (Im) and its conjugate acid (HIm+) needed to prepare a pH 7.49 buffer solution?

3.2

What is the pH of a 0.00037 M solution of nitric acid?

3.4

What is the hydroxide ion concentration of a 3.0 M Aniline (C6H5NH2) solution

3.5e-5 M

Calculate the mass of Ag2CO3(s) produced by mixing 125 mL of 0.315 M Na2CO3(aq) and 75.0 mL of 0.155 M AgNO3(aq) and calculate the number of moles of the excess reactant remaining in solution. (molar mass of Ag2CO3 = 275.8 g/mole) 2Ag+ (aq) + CO3 2- (aq) --> Ag2CO3(s) Note: Na2CO3(s) --> 2Na+ + CO3 2- (aq) AgNO3(s) --> Ag+ (aq) + NO3 - (aq)

33.6 mmoles or 0.0336 moles

Calculate the mass of Ag2CO3(s) produced by mixing 39.4 mole of CO3 2- (aq) and 11.6 mole of Ag+ (aq) and calculate the number of moles of the excess reactant remaining in solution. (molar mass of Ag2CO3 = 275.8 g/mole) 2Ag+ (aq) + CO3 2- (aq) --> Ag2CO3(s)

33.6 moles

What is the pH of the buffer that results when 20.6 g sodium acetate (NaCH3CO2) is mixed with 459.4 mL of 1.4 M acetic acid (CH3CO2H) and diluted with water to 1.0 L?

4.36

What is the pH of the buffer that results when 30.8 g sodium acetate (NaCH3CO2) is mixed with 510.3 mL of 1.8 M acetic acid (CH3CO2H) and diluted with water to 1.0 L?

4.36

A solution was prepared by dissolving 0.0195 mole of propionic acid and 0.0170 mole of sodium propionate in 1.00 L? What would be the pH of the solution in beaker after 1.93 mL of 0.0106 M HCl were added to 10.0 mL of the prepared solution?

4.73

A classic 1969 Ford mustang has a 289 cubic inch engine. Car engines today are sold in liters. What is the engine size of that ford engine in liters? 1 inch= 2.54 cm.You do not neet to enter units. Make sure to answer with 3 significant figures.

4.74

How many atoms of hydrogen are found in 0.400 mol of H2S note: use programmers notation

4.82e23

The combustion of 0.0272 mole of a hydrocarbon produces 1.9609 g H2O and 3.5927 g CO2. What is the molar mass of the hydrocarbon in g/mole unit?

The combustion of 0.0272 mole of a hydrocarbon produces 1.9609 g H2O and 3.5927 g CO2. What is the molar mass of the hydrocarbon in g/mole unit? Please answer with 2 significant figures.

A metal, M, forms an oxide having the formula MO2 containing 59.93% metal by mass. Determine the atomic weight in g/mole of the metal (M). Please provide your answer in 2 decimal places.

47.86

Titanium has five naturally occuring elements. The reported mass of all the isotopes are: % natural abundance and atomic mass: - 7.930%, 45.96 amu - 7.280%, 46.95 amu - 73.94%, 47.95 amu - 5.510%, 48.95 amu - 5.340%, 49.95 amu Based on this data, what is titanium's average atomic mass? (make sure to answer with 2 decimal places and unit)

47.88 amu

Calculate the number of mmoles of the excess reactant remaining in solution when mixing 117.4 mL of 0.497 M Na2CO3(aq) and 71.6 mL of 0.249 M AgNO3(aq) (molar mass of Ag2CO3 = 275.8 g/mole) 2Ag+(aq) + CO32-(aq) → Ag2CO3(s) Note: Na2CO3(s) → 2Na+ + CO32-(aq) AgNO3(s) → Ag+ (aq) + NO3-(aq)

49.4 mmol

3.15 g of 1-methylcyclohexene is reacted with 2.89 g of Cl2 to form (1R,2R)-1,2-dichloro-1-methylcyclohexane. What is the theoretical yield in grams of (1R,2R)-1,2-dichloro-1-methylcyclohexane for this reaction?

5.47 g

Calculate the mass of Fe(OH)3(s) produced by mixing 60.0 mL of 0.153 M KOH(aq) and 35.0 mL of 0.255 M Fe(NO3)3(aq), and the number of moles of excess reactant remaining in solution.

5.87 mmoles or 0.00587 moles

Chromium has four naturally occuring elements. The reported mass of all the isotopes are: fractional abundance Atomic mass 0.04350 49.9461 0.8379 51.9405 0.09500 52.9407 0.02360 53.9389 Based on this data, what is chromium's average atomic mass? (make sure to answer with 2 decimal places and unit)

51.99 amu

Iron has four naturally occuring elements. The reported mass of all the isotopes are: fractional abundance Atomic mass 0.05845 53.9396 0.9175 55.9349 0.02119 56.9354 0.002860 57.9333 Based on this data, what is irons's average atomic mass? (make sure to answer with 2 decimal

55.85

From the mass spectrum of Krypton (atomic number = 36) shown, determine the fractional abundance (%) of the isotope with mass of 84 amu.

60%

How many mL of 0.3 M HCl(aq) would you need to neutralize (react completely) with 175.5 mL of 0.562 M Ca(OH)2(aq) solution? 2HCl(aq) + Ca(OH)2(aq) → CaCl2(aq) + 2H2O(l) Note: HCl(aq) → H+(aq) + Cl-(aq) Ca(OH)2(aq) → Ca2+(aq) + 2OH-(aq)

658 mL

658 ml

The active ingredient in Milk of Magnesia, a commonly used laxative, is magnesium hydroxide. A 2.0-teaspoon sample of Milk of Magnesia was analyzed and required 18.26 mL of a 1.50 M hydrochloric acid for complete neutralization. Calculate the mass percent concentration of magnesium hydroxide in Milk of Magnesia given that the density of Milk of Magnesia is 1.1 g/mL

7.34%

A 0.600 mol sample of Cu2S is roasted in excess oxygen to yield copper metal and sulfur dioxide. Calculate the mass of copper metal produced. Cu2S + O2 → 2Cu + SO2

76.3 g

A 0.600 mol sample of Cu2S is roasted in excess oxygen to yield copper metal and sulfur dioxide. Calculate the mass of copper metal produced. Cu2S + O2 → 2Cu + SO2 Need to answer with units on this question. For example if the answer is 111 grams you can write: 111 g 1.11e2 g

76.3 g

Exactly 33.2 mL of 0.2 M HNO2 are titrated with a 0.2 M NaOH solution. What is the pH at the equivalence point

8.14

Exactly 49.0 mL of 0.4 M HNO2 are titrated with a 0.4 M NaOH solution. What is the pH at the equivalence point ?

8.3

What mass of iodine contains the same number of atoms as 25.0 grams of chlorine?

89.48 g

What is the hydroxide concentration of a 1.93 M benzoic acid solution?

9.1E-13 M

Calculate the volume in mL of a 3.86 M KF (aq) solution that should be used to prepare 250. mL of 0.150 M KF(aq). Your answer should include the appropriate unit.

9.715 mL

Calculate the volume in mL of a 3.86 M KF (aq) solution that should be used to prepare 250. mL of 0.150 M KF(aq). Your answer should include the appropriate unit.

9.72 mL

Indicate whether each of the following statements is true or false: A. A certain mass of solid Na contains fewer atoms than the same mass of gaseous Ar. B. On average, one Li atom weighs 6.941 grams. C. A certain mass of solid Na contains fewer atoms than the same mass of gaseous Ne. D. The average atomic mass of an unknown monatomic gas is 0.045 g/mol. E.Every H atom weighs 1.008 amu.

A. False B. False C. True D. False E. False

What is the formula of the compound corresponding to the combination of aluminum and sulfur.

Al2S3

Which compound is the strongest acid? Select one: a. A b. B c. C d. D e. E

B the one wih Cl

Which compound will give an M+2 peak? Select one: a. CH3CH2OH b. CH3Br c. CH3CO2H d. CH3CH2NH2 e. (CH3)2NCH2C≡N

B. CH3Br

Which statement explains why HBr is a stronger acid than HF? Select one: a. Br- is more stable than F- because Br- is larger than F-. b. Br- is less stable than F- because Br- is larger than F-. c. Br- is more stable than F- because Br- is less electronegative than F-. d. Br- is less stable than F- because Br- is less electronegative than F-.

Br- is more stable than F- because Br- is larger than F-.

Which gas has the greatest density at 25 °C and 1 atm? a. O2 b. Ar c. N2 d. F2 e. C3H8

C3H8

A 1.367 g sample of an organic compound was combusted in a stream of air to yield 3.002 g carbon dioxide and 1.640 g water. If the original compound contained only C, H and O, what is its empirical formula? provide your answer as:

C3H8O

Propose a possible molecular formula for a compound containing one oxygen with the mass spectrum below.

C4H9NO

Propose a possible molecular formula for a compound containing one oxygen with the mass spectrum below. (look at picture)

C4H9NO

Which compound will give an M+ and M+2 peak with an intensity ratio of 1:1? Select one: a. CH3CH2Cl b. CH3NH2 c. CH3CO2H d. CH3CH2Br e. (CH3)2NCH2C≡N

CH3CH2Br

Which compound will give an M+ and M+2 peak with an intensity ratio of 3:1? Select one: a. CH3CH2Cl b. CH3NH2 c. CH3CO2H d. CH3CH2Br e. (CH3)2NCH2C≡N

CH3CH2Cl

Identify the atom from the given mass spectrum. (The graph shows a bar at 151 amu and 153 amu)

Identify the excess reactant (HCl or NaOH), if any, and its final molar concentration when 1.75 g of NaOH(s) is stirred into 125.0 mL of 0.250 M HCl(aq).

Excess reactant is NaOH. Final concentration of NaOH = 0.100 M

10FeSO4(aq) + 2KMnO4(aq) + 8H2SO4(aq) → 5Fe2(SO4)3(aq) + 2MnSO4(aq) + K2SO4(aq) + 8H2O(l) Name all of the molecules in the reaction

FeSO4 = Iron(II) sulfate KMnO4 = Potassium permanganate H2SO4 = Sulfuric acid Fe2(SO4)3 = Iron(III) sulfate MnSO4 = Manganese(II) sulfate K2SO4 = Potassium sulfate

A compound X shows a molecular ion peak at m/z 72 in its mass spectrum, and a strong peak at ~1715 cm-1 in its IR spectrum. Which structures are possible for compound X?

Rank compounds in order of decreasing acidity, putting the most acidic first.

III > I > II

Rank compounds in order of decreasing acidity, putting the most acidic first. Select one: a. IV > II > III > I b. III > II > IV > I c. I > II > IV > III d. III > IV > II > I

III > IV > II > I

The base peak in a mass spectrum corresponds to the most stable fragment. Propose a structure for a compound that is consistent with the following data.a) The molecular ion peak has m/z = 116b) The base peak is at m/z = 59.c) The compound is composed of C, H and O atoms.d) The IR spectrum shows a strong absorbance at 3257 cm-1.

Rank compounds in order of decreasing acidity, putting the most acidic first.

IV > III > II > I

A compound gave on analysis the following percent composition: K = 26.57% Cr= 35.36% O= 38.07% What is the emperical formula for this compound?

K2Cr2O7

Identify the atom from the given mass spectrum.

What is the formula of the compound corresponding to the combination of magnesium and phosphate?

Mg3(PO4)2

A compound gave on analysis the following percent composition: Na =21.6% Cl= 33.3% O= 45.1% What is the emperical formula for this compound?

NaClO3

What is the effect of reducing the volume on the system described below? 2C(s) + O2(g) ↔ 2CO(g) Select one: a. Shifts toward reactants. b. Shifts towards products c. Remains unchanged

Shifts toward reactants.

Which of the following statements about the base peak of a mass spectrum is always true? Select one: a. The base peak corresponds to the molecular ion. b. The base peak corresponds to the most abundant ion. c. The base peak corresponds to the lowest m/z. d. None of the above.

The base peak corresponds to the most abundant ion.

If the ratio of base to acid in a buffer increases by a factor of 10, the pH of the buffer Select one: a. increases by 1. b. decreases by 10. c. decreases by 1. d. remains unchanged. e. increases by 10.

The correct answer is: increases by 1.

Indicate which are potential acids. Select one or more: a. HPO42- b. F- c. CH3NH3+ d. Al3+ e. NH4+ f. H2O

The correct answers are: Al3+, CH3NH3+, HPO42-, NH4+, H2O

Given the following system at equilibrium: N2(g) + 2O2(g) ↔ 2NO2 (g) + heat What is the effect on the equilibrium if you increase the reaction vessel volume? Select one: a. The equilibrium will shift towards reactants. b. The equilibrium will not shift. c. The equilibrium will shift towards products.

The equilibrium will shift towards reactants.

elect all conditions is/are met at the equivalence point of the titration of a monoprotic weak base with a strong acid? Select one or more: a. The pH of the solution is less than 7.00. b. The volume of acid added from the buret must equal the volume of base titrated. c. The pH of the solution is more than 7.00. d. The pH of the solution is equal to 7.00. e. The moles of acid added from the buret equals the initial moles of weak base. f. The concentration of acid added from the buret must equal the concentration of base titrated.

The moles of acid added from the buret equals the initial moles of weak base., The pH of the solution is less than 7.00.

What type of signal(s) would you observe in the mass and (or) infrared spectrum of the following compound? (It's a plus sign looking CARBON with a Cl on the Top Carbon)

Two mass peaks at 92 and 94 amu

A tightly sealed 4.0-L flask contains 884 torr of N2 at 94.0 °C. The flask is cooled until the pressure is reduced 442 torr. What is the temperature of the gas?

a. -47.0 °C b. 47.0 °C c. -89.5 °C d. 184 °C e. 188 °C

Determine the % ionization of 1 M hydrocyanic acid (HCN), Ka = 4.0 e-10 a. 0.002 % b. 0.2 % c. 0.4 % d. 0.004 % e. 1 %

a. 0.002 %

What is the temperature and presure at STP? Select one: a. 0°C and 1 atm b. 25°C and 1 atm c. 0°C and 0 atm d. 25°C and 0 atm e. 273.15 °C and 1 atm

a. 0°C and 1 atm

Which of these substances has an abundant and distinctive molecular fragment in its mass spectrum at m/z = 93 and 95? a. 1-bromobutane b. (2,2-dimethylpropyl)benzene c. (3-methylbutan-2-yl)benzene d. 4-methylhexan-3-one e. 3-methylhexan-2-one

a. 1-bromobutane

What is the pH of a 0.75 M NaF solution? Select one: a. 8.52 b. 1.73 c. 12.27 d. 7.00 e. 5.48

a. 8.52

Which compound will give an M+2 peak? Select one: a. CH3CH2Cl b. CH3NH2 c. CH3CO2H d. CH3CH2NH2 e. (CH3)2NCH2C≡N

a. CH3CH2Cl

Which compound is the weakest acid? Select one: a. HF b. HCl c. HBr d. HI

a. HF

A compound X shows a molecular ion peak at m/z 72 in its mass spectrum, and a strong peak at ~1715 cm-1 in its IR spectrum. Which structures are possible for compound X? a. I b. II c. III d. I and II

a. I

A compound X shows a molecular ion peak at m/z 72 in its mass spectrum, and a strong peak at ~1715 cm-1 in its IR spectrum. Which structures are possible for compound X? a. I b. II c. III d. I and II

a. I

If the volume of a confined gas is expanded to four times the original volume while its temperature remains constant, what change will be observed? Select one: a. The pressure of the gas will decrease to 1/4 its original value. b. The pressure of the gas will decrease to 1/2 its original value. c. The pressure of the gas will remain unchanged. d. The pressure of the gas will increase to twice its original value. e. The pressure of the gas will increase to four times its original value.

a. The pressure of the gas will decrease to 1/4 its original value

a. The pressure of the gas will decrease to 1/4 its original value.

A compound X has a molecular ion peak in its mass spectrum at m/z 136. What information does this tell us about X? a. X has a molecular mass of 136. b. The molecular formula for X is C8H8O2. c. The empirical formula for X is C4H4O. d. Both A (X has a molecular mass of 136) and B (The molecular formula for X is C8H8O2) are true. e. Statements (X has a molecular mass of 136), (The molecular formula for X is C8H8O2), and (The empirical formula for X is C4H4O) are all true.

a. X has a molecular mass of 136.

A compound X has a molecular ion peak in its mass spectrum at m/z 136. What information does this tell us about X? Select one: a. X has a molecular mass of 136. b. The molecular formula for X is C8H8O2. c. The empirical formula for X is C4H4O. d. Both A (X has a molecular mass of 136) and B (The molecular formula for X is C8H8O2) are true. e. Statements (X has a molecular mass of 136), (The molecular formula for X is C8H8O2), and (The empirical formula for X is C4H4O) are all true.

a. X has a molecular mass of 136.

Which of these substances has an abundant and distinctive molecular fragment in its mass spectrum at m/z = 77? a. bromobenzene b. butan-1-amine c. butan-2-amine d. pentan-2-one e. pentan-3-one

a. bromobenzene

A compound X shows a molecular ion peak at m/z 72 in its mass spectrum, and a strong peak at ~1715 cm-1 in its IR spectrum. Which structures are possible for compound X? a. i b. ii c. iii d. i and ii

a. i

Write the name for the following compound:(NH4)2CrO4

ammonium chromate

Nitric oxide is made from the oxidation of ammonia. What mass of nitric oxide can be made from the reaction of 8.00 g NH3 with 17.0 g O2? 4 NH3(g) + 5 O2(g) →→ 4 NO(g) + 6 H2O(g) a. 4.54 g b. 12.8 g c. 14.1 g d. 15.9 g e. 25.0 g

b. 12.8 g

A metal, M, forms an oxide having the formula M2O3 containing 52.92% metal by mass. Determine the atomic weight of the metal (M). a. 55.85 g/mol b. 26.98 g/mol c. 58.93 g/mol d. 53.96 g/mol e. 63.55 g/mol

b. 26.98 g/mol

36.6 L of He gas at STP is pumped into a 10.0-L tank containing 1.0 atm of O2 at 25 °C. What is the total pressure in a tank at 25 °C? a. 2.0 atm b. 5.0 atm c. 5.4 atm d. 8.0 atm e. 8.8 atm

b. 5.0 atm

Which compound will give an M+2 peak? Select one: a. CH3CH2OH b. CH3Br c. CH3CO2H d. CH3CH2NH2 e. (CH3)2NCH2C≡N

b. CH3Br

The equilibrium constant reaction (Kc) for the reaction below is 0.12.2 SO3(g) 2 SO2(g) + O2(g)If a flask is filled with 0.1 M SO3, 0.08 M SO2, and 0.16 M O2, predict the direction of the equilibrium as the reaction is reaching equilibrium by using Q, the reaction quotient. Select one: a. Forward because Q > K. b. Forward because Q < K. c. Reverse because Q < K. d. Reverse because Q > K. e. The reaction is at equilibrium because Q = K.

b. Forward because Q < K.

Which compound has the lowest pKa? Select one: a. H2O b. H2S c. NH3 d. CH4

b. H2S

Which concept can be used to explain the difference in acidity between ethanol (CH3CH2OH) and 2-fluoroethanol (FCH2CH2OH)? Select one: a. Size b. Inductive effect c. Resonance d. Hybridization

b. Inductive effect

In which equilibrium system(s) will an increase in the pressure cause the reaction to shift to the right? Select one or more: a. H2(g) + F2(g) 2 HF(g) b. N2(g) + 3 H2(g) 2 NH3(g) c. CaCO3(s) CaO(s) + CO2(g) d. 2 NOBr(g) 2 NO(g) + Br2(g) e. 2 H2O(g) + O2(g) 2 H2O2(g)

b. N2(g) + 3 H2(g) 2 NH3(g) and e. 2 H2O(g) + O2(g) 2 H2O2(g)

Which of the following statements about the base peak of a mass spectrum is always true? a. The base peak corresponds to the molecular ion. b. The base peak corresponds to the most abundant ion. c. The base peak corresponds to the lowest m/z. d. None of the above.

b. The base peak corresponds to the most abundant ion.

Which of these substances has an abundant and distinctive molecular fragment in its mass spectrum at m/z = 30? a. bromobenzene b. butan-1-amine c. butan-2-amine d. pentan-2-one

b. butan-1-amine

What class of compounds is most likely to give a fragment ion at m/z = 77?

benzene derivatives

Which of these substances has an abundant and distinctive molecular fragment in its mass spectrum at m/z = 30?

butan-1-amine

A metal, M, forms an oxide having the formula MO2 containing 59.93% metal by mass. Determine the atomic weight of the metal (M). a. 53.96 g/mol b. 55.85 g/mol c. 47.87 g/mol d. 58.93 g/mol e. 63.55 g/mol

c. 47.87 g/mol

Which species is the conjugate base of the hydronium ion, H3O+? Select one: a. H3O b. H2O- c. H2O d. HO-

c. H2O

What is the most acidic proton on this molecule? Select one: a. HA b. HB c. HC d. HD e. HE

c. HC

Which gas has the lowest density at 25 °C and 1 atm? Select one: a. O2 b. Ar c. N2 d. F2 e. C3H8

c. N2

You observe a compound that exhibits a mass spectrum with peak at 160 and a peak at 162, both of equal intensity. This compound contains: a. Two chlorine atoms b. One iodine atom c. One bromine atom d. Two bromine atoms

c. One bromine atom

You observe a compound that exhibits a mass spectrum with peak at 160 and a peak at 162, both of equal intensity. This compound contains: Select one: a. Two chlorine atoms b. One iodine atom c. One bromine atom d. Two bromine atoms

c. One bromine atom

What class of compounds is most likely to give a fragment ion at m/z = M-18? a. alkenes b. cycloalkanes c. alcohols d. alkyl iodides e. benzene derivatives

c. alcohols

What class of compounds is most likely to give a fragment ion at m/z = M-18? Select one: a. alkenes b. cycloalkanes c. alcohols d. alkyl iodides e. benzene derivatives

c. alcohols

If 0.10 M aqueous solutions are prepared of each of the acids, which produces the solution with the highest pH? Select one: a. benzoic acid b. acetic acid c. hydrocyanic acid d. hydrogen sulfite ion e. hypochlorous acid

c. hydrocyanic acid

What molecule is most likely to give a fragment ion at m/z = M-45? a. cyclohexene b. 2-bromopropane c. propanoic acid d. toluene e. carbon dioxide

c. propanoic acid

Write systematic nomenclature for the following molecule HClO3

chloric acid

What is the pH of a 0.20 M Ca(OH)2 solution? Select one: a. 0.40 b. 0.60 c. 7.00 d. 13.60 e. 13.40

d. 13.60

What is the pH of a 0.20 M Ca(OH)2 solution? Select one: a. 0.60 b. 7.00 c. 0.40 d. 13.60 e. 13.40

d. 13.60

What is the pH of a solution that results from diluting 0.20 mol acetic acid (CH3CO2H) and 0.30 mol sodium acetate (NaCH3CO2) with water to a volume of 1.0 L? Select one: a. 4.35 b. 4.59 c. 4.77 d. 4.95 e. 5.14

d. 4.95

Which compound will give an M+ and M+2 peak with an intensity ratio of 1:1? Select one: a. CH3CH2Cl b. CH3NH2 c. CH3CO2H d. CH3CH2Br e. (CH3)2NCH2C≡N

d. CH3CH2Br

Which compound will give a molecular ion having m/z = an odd number? Select one: a. CH3CH2OH b. CH2BrCl c. CH3CO2H d. CH3CH2NH2 e. (CH3)2NCH2C≡N

d. CH3CH2NH2

Which statement explains why H2O is a stronger acid than CH4? Select one: a. H2O can form hydrogen bonds while CH4 cannot. b. H2O forms a less stable conjugate base, HO-. c. CH4 forms a more stable conjugate base, CH3-. d. H2O forms a more stable conjugate base, HO-.

d. H2O forms a more stable conjugate base, HO-.

Which species is the conjugate acid of ammonia, NH3? Select one: a. H4N b. H3N+ c. H2N- d. H4N+

d. H4N+

Which concept can be used to explain the difference in acidity between acetylene (C2H2) and ethylene (C2H4)? Select one: a. Size b. Resonance c. Inductive effect d. Hybridization

d. Hybridization

d. IV

Which compound is the strongest acid? Select one: a. I b. II c. III d. IV

d. IV

Which combination would be best to buffer an aqueous solution at a pH of 9.0? Select one: a. HNO2 and NO2- b. CH3CO2H and CH3COO- c. H3PO4 and H2PO4- d. NH4+ and NH3 e. H2PO4- and HPO42-

d. NH4+ and NH3

Consider the reaction A(aq) 2 B(aq) where Kc = 4.1 at 25 °C. If 0.50 M A(aq) and 1.5 M B(aq) are in a flask, predict the direction of the equilibrium as the reaction is reaching equilibrium by using Q, the reaction quotient. Select one: a. Forward because Q > K. b. Forward because Q < K. c. Reverse because Q < K. d. Reverse because Q > K. e. The reaction is at equilibrium because Q = K.

d. Reverse because Q > K.

Which statement about acid strength is true? Select one: a. The stronger the acid, the further the equilibrium lies to the left. b. The stronger the acid, the smaller the Ka. c. The stronger the acid, the larger the pKa. d. The stronger the acid, the smaller the pKa.

d. The stronger the acid, the smaller the pKa.

What type of signal(s) would you observe in the mass and (or) infrared spectrum of the following compound? a. A signal at 1600 cm-1 b. A signal at 3300 cm-1 c. A single mass peak at 92 amu d. Two mass peaks at 92 and 94 amu

d. Two mass peaks at 92 and 94 amu

An important endothermic gas phase reaction for the commercial production of hydrogen is CH4(g) + H2O(g) ↔ 3H2(g) + CO(g) What will happen to the number of moles of hydrogen at equilibrium when carbon monoxide is removed? Select one: a. decreases b. need the equilibrium constant to determine if a change occurs c. no change d. increases

d. increases

d. iv

Which of these substances has an abundant and distinctive molecular fragment in its mass spectrum at m/z = 43 and 71? a. bromobenzene b. butan-1-amine c. butan-2-amine d. pentan-2-one e. pentan-3-one

d. pentan-2-one

The compound P4S3 is used in matches. It reacts with oxygen to produce P4O10 and SO2. The unbalanced chemical equation is shown below. P4S3(s) + O2(g) → P4O10(s) + SO2(g) What mass of SO2 is produced from the combustion of 0.401 g P4S3? a. 0.134 g b. 1.20 g c. 0.0389 g d. 0.117 g e. 0.350 g

e. 0.350 g

The compound P4S3 is used in matches. It reacts with oxygen to produce P4O10 and SO2. The unbalanced chemical equation is shown below.P4S3(s) + O2(g) → P4O10(s) + SO2(g)What mass of SO2 is produced from the combustion of 0.401 g P4S3? Select one: a. 0.134 g b. 1.20 g c. 0.0389 g d. 0.117 g e. 0.350 g

e. 0.350 g

What is the pH after 25.2 mL of 3.5 M NaOH have been added to 25.00 mL of 4.2 M HF? Select one: a. 1.76 b. 13.5 c. 7.00 d. 14.5 e. 3.89

e. 3.89

What class of compounds is most likely to give a fragment ion at m/z = 77? a. alkenes b. cycloalkanes c. alcohols d. alkyl iodides e. benzene derivatives

e. benzene derivatives

Write the name for the following compound: LiCN

lithium cyanide

Write systematic nomenclature for the following molecule Mg(IO)2

magnesium hypoiodite

Calculate the mass of Ag2CO3(s) produced by mixing 125 mL of 0.315 M Na2CO3(aq) and 75.0 mL of 0.155 M AgNO3(aq) and the number of moles of the excess reactant remaining in solution. Your calculations will be more efficient if you realize that 1 M = 1 mmol/mL and that molar masses can be expressed as mg/mmol as well as g/mol where 1 mmol = 0.001 mol.

mass of Ag2CO3(s) produced = 1.65 g moles of the excess reactant (Na2CO3) remaining in solution = 0.033 mole molarity of the excess reactant (Na2CO3) remaining in solution = 0.165 M

Which of these substances has an abundant and distinctive molecular fragment in its mass spectrum at m/z = 43 and 71?

pentan-2-one

What molecule is most likely to give a fragment ion at m/z = M-45?

propanoic acid

The atomic mass of rhenium is 186.2. Given that 37.1% of natural rhenium is rhenium-185, what is the other stable isotope?

Chem Final Exam Review (Minus Unit 4)

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