Chem 112 Exam 2
Which of the following statements is false? A. Both exothermic and endothermic reactions can be spontaneous B. Spontaneous processes proceed on their own without any outside assistance C. Thermodynamics can tell use about the direction, extent, and speed of a chemical reaction D. The sum of the entropy change of a system and the entropy change of its surroundings for any spontaneous process is always greater than zero E. Entropy generally increases with increasing temperature, volume, and the number of moving particles
C.
A 0.1 M solution of an electrolyte has a pH of 4.0 What is the electrolyte? A. a strong acid B. a strong base C. a weak acid D. a weak base E. a salt of a strong acid and a strong base
C.
The pH of a 0.500 M solution of K₂H₃O₂is A. less than 7 B. 7 C. greater than 7
C.
Which of the following does not dictate the rate of a chemical reaction? A. Activation Energy B. Collision Frequency C. Thermodynamics
C.
Which of the following statements about entropy is true? A. Entropy is not a state function B. It must be negative for a process to be spontaneous C. The more disorder a system has, the greater it's entropy D. The entropy of a perfect crystalline substance is zero at room temperature
C.
Which of the following will give an acidic solution when dissolved in water? i. Fe(NO₃)₃ ii. NaCl iii. NH₄Cl iv. NaF A. i only B. ii and iv C. i and iii D. iii only E. i, ii, and iii
C.
Which of the following will have the highest gas-phase molar entropy at 25°C? A. H₂ B. C₂H₆ C. C₃H₈ D. C₂H₄ E. CH₄
C.
What is the H⁺ concentration in a solution with a pH of 3.75? A. 5.6 x 10³ M B. 7.5 x 10⁻³ M C. 5.6 x 10⁻¹¹ M D. 1.8 x 10⁻⁴ M E. 2.5 x 10⁻⁸ M
D.
What is the conjugate acid of water? A. H₂O B. OH⁻ C. H⁺ D. H₃O E. HCl
D.
What is the pH of a 0.014 M Ca(OH)₂ solution? A. 1.9 B. 1.6 C. 12.1 D. 12.4 E. 15.9
D.
Which changes occur when solid NaF is added to a 0.1 M solution of HF? i. pH decreases ii. Ka increases iii. [F] decrease iv. [HF] increases A. i only B. ii only C. iii only D. iv only E. i, iii, and iv
D.
Which reaction below should have an increase in entropy? A. 2 H₂ (g) + O₂ (g) → 2 H₂O (g) B. 2 NO₂ (g) → N₂O₄ (g) C. Ag⁺ (aq) + Cl⁻ (aq) → AgCl (s) D. 2 HgO (s) → 2 Hg (l) + O₂ (g) E. N₂ (g) → N₂ (l)
D.
Which species is the acid in the following reaction? HCl(aq) + H₂O(l) ⇌ H₃O+(aq) + Cl-(aq)
HCl(aq)
Which species is the acid in the following reaction? NH₃(aq) + H₂O(l) ⇌ NH₄+(aq) + OH-(aq)
H₂O(l)
Which species is the base in the following reaction? HCl(aq) + H₂O(l) ⇌ H₃O+(aq) + Cl-(aq)
H₂O(l)
Which species is the conjugate acid in the following reaction? HCl(aq) + H₂O(l) ⇌ H₃O+(aq) + Cl-(aq)
H₃O+(aq)
The equilibrium expression for the autoionization of water is given by:
Kw = [H₃O+][OH-]
The acid-base properties of water produces H₃O+ and OH- ions in equilibrium with water in a reaction known as..
autoionization of water
A Lewis acid is... a) a substance that can donate a pair of electrons b) a substance that can accept a pair of electrons c) a substance capable of donating a proton d) a substance capable of accepting a proton
b)
What is an Arrhenius base? a) Any compound capable of accepting a H+ ion b) Any compound that releases OH- when dissolved in H₂0 c) Any compound that releases H+ when dissolved in H₂O d) Any compound capable of donating a H+ ion
b)
What is the formula for aqua regia? a) HCl b) HNO₃ + HCl c) H₂ d) CH₃COOH
b)
When K_b > K_a, the solution is a) acidic b) basic c) neutral
b)
Which choice below will increase the pH of a 0.2 M H₂S solution? a) Bubble through more H₂S (s) b) Addition of Na₂S (s) c) Addition of MgCl₂ (s) to form a solid precipitate of MgS d) Addition of NaCl (s) e) Addition of HNO₃ (aq)
b)
Which element has the most metallic character? a) Na b) K c) Mg d) Co e) Al
b)
Which of the following bases is the strongest? a) Ammonia (Kb = 1.8 x 10⁻⁵) b) Methylamine (Kb = 4.4 x 10⁻⁴) c) Nicotine (Kb = 7 x 10⁻⁷) d) Hydroxylamine (Kb = 1.1 x 10⁻⁸)
b)
Which of these compounds is a basic oxide? a. CO₂ b. MgO c. As₂O₃ d. SO₂ e. Cl₂O₇
b.
Is HBr a strong or a weak acid?
strong
Is HBrO₄ a strong or a weak acid?
weak
Is HF a strong or a weak acid?
weak
Is H₂SO₄ a strong or a weak acid?
weak
pH
The negative base-10 logarithm of the hydronium ion concentration (in mol/L)
conjugate base
The newly formed species when a Bronsted acid donates a proton,
conjugate acid
The newly formed species when a Bronsted base accepts a proton
T/F: A mixture of 100 mL of 0.1 M CH₃COOH and 50 mL of 0.1 M NaOH will result in a buffer solution
True
T/F: A spontaneous reaction can do work
True
T/F: All alkali metal oxides and all alkali earth metal oxides except BeO are basic
True
T/F: Beryllium oxide and several metallic oxides in Groups 3A and 4A are amphoteric
True
T/F: Enthalpy alone doesn't determine spontaneity
True
T/F: For weak acids, [H⁺] final < [HX] initial
True
T/F: Processes that are spontaneous in one direction are nonspontaneous in the reverse direction
True
T/F: Pure water does not contain species that can consume acids or bases
True
T/F: Starting with the molar concentration and K_a of a weak monoprotic acid, we can use an equilibrium table to determine pH
True
T/F: Strong acids dissociate completely when dissolved in water
True
T/F: The best buffer has a pH equal to the pKa of the conjugate acid
True
T/F: The conjugate of a weak acid will be a weak base
True
T/F: The highest capacity buffer has the highest concentration of a 1:1 mixture of conjugate acid and conjugate base
True
T/F: The larger the value of K_a, the acid ionization constant, the stronger the acid
True
T/F: The range of a buffer is within 1 pH unit of the pKa of the conjugate acid
True
T/F: The strength of an acid is measured by its tendency to ionize
True
T/F: The stronger the acid, the weaker its conjugate base
True
T/F: Weak acids only partially dissociate when dissolved in water
True
T/F: When [H₃O+] < [OH-], the solution is basic
True
T/F: When [H₃O+] = [OH-], the solution is neutral
True
T/F: When the cation of a salt is the conjugate acid of a weak base, a solution of the salt will be acidic
True
Buffer
a solution that contains a weak acid and its conjugate base (or a weak base and its conjugate acid)
amphoteric
a species that can behave either as a Bronsted acid or a Bronsted base
A Lewis base is... a) a substance that can donate a pair of electrons b) a substance that can accept a pair of electrons c) a substance capable of donating a proton d) a substance capable of accepting a proton
a)
Adding water to a 0.100 M solution of nitric acid causes the pH to a) increase b) decrease c) stay the same
a)
An oxide is amphoteric. Under what conditions will it be least soluble? i) in pure water (pH = 7) ii) in acid solution (pH = 3) iii) in basic solution (pH = 11) a) i b) ii c) iii d) i and ii e) i and iii
a)
Identify the compound(s) that act as acid(s) in the following equilibrium: NH₄⁺(aq) + CN⁻ (aq) ⇌ NH₃ (aq) + HCN (aq) a) NH₄⁺ and HCN b) NH₄⁺ and NH₃ c) NH₄⁺ only d) NH₃ only e) HCN only
a)
Identify the weak electrolytes among the following: HNO₃, NaClO₂, HClO₂, NH₄Br, H₂SO₄ a) HClO₂ only b) H₂SO₄ and HNO₃ c) HNO₃, H₂SO₄, and HClO₂ d) NaClO₂ and NH₄Br e) HClO₂, NaClO₂, and NH₄Br f) All of them are weak electrolytes g) None of them are weak electrolytes
a)
What is an Arrhenius acid? a) any compound that releases H+ when dissolved in H₂O b) Any compound that releases OH- when dissolved in H₂0 c) Any compound capable of donating a H+ ion d) Any compound capable of accepting a H+ ion
a)
When K_b < K_a, the solution is a) acidic b) basic c) neutral
a)
Which of the following oxyacids would be the weakest? a) HIO b) HBrO c) HClO₂ d) HClO₃ e) HIO₃
a)
Which one of the following ions will produce a basic solution in water? a) ClO⁻ b) NH₄⁺ c) Cu²⁺ d) NO₃⁻ e) Cl⁻
a)
Arrange the following Bronsted bases in order of decreasing basicity: NO₂⁻, ClO⁻, BrO⁻, IO₄⁻ a) IO₄⁻ > NO₂⁻ > BrO⁻ > ClO⁻ b) ClO⁻ > BrO⁻ > IO₄⁻ > NO₂⁻ c) ClO⁻ > BrO⁻ > NO₂⁻ > IO₄⁻ d) BrO⁻ > ClO⁻ > NO₂⁻ > IO₄⁻ e) BrO⁻ > ClO⁻ > IO₄⁻ > NO₂⁻
d)
Oxoacids contain a) hydrogen b) oxygen c) a central nonmetal atom d) all of the above
d)
Stong acids 1. are strong electrolytes 2. have strong conjugate bases 3. have extremely large Ka values a) 1, 2 and 3 b) 1 and 2 c) 2 and 3 d) 1 and 3 e) 2 only
d)
What is a Bronsted Base? a) any compound that releases H+ when dissolved in H₂O b) Any compound that releases OH- when dissolved in H₂0 c) Any compound capable of donating a H+ ion d) Any compound capable of accepting a H+ ion
d)
Which of the following salts will give the most basic solution when dissolved in water? a) KBrO₄ b) KBrO₃ c) KBrO₂ d) KBrO e) KClO₄
d)
Which of the following statements is false? a) Citric acid tastes sour b) Hydrochloric acid corrodes many metals, usually releasing hydrogen gas c) Acetic acid is a weak acid d) The percentage dissociation is greater for 0.01 M acetic acid than for 0.001 M acetic acid e) HBr dissociates completely in aqueous solution
d)
Which of these is not a physical property of bases? a) dissolve oil and grease b) slippery to touch c) react with metal ions to form precipitates d) sour taste e) turns litmus paper blue
d)
Which reaction corresponds to the Kb for HSO₄⁻? a) H₂SO₄ ⇌ H⁺ + HSO₄⁻ b) SO₄²⁻ + H₂O ⇌ OH⁻ + HSO₄⁻ c) HSO₄⁻ + OH⁻ ⇌ H₂O + SO₄²⁻ d) HSO₄⁻ + H₂O ⇌ OH⁻ + H₂SO₄ e) HSO₄⁻ ⇌ H⁺ + SO₄²⁻
d)
List the strong acids...(In the order from the ppt)
1. HNO₃ 2. HClO₃ 3. HClO₄ 4. HCl 5. HBr 6. HI 7. H₂SO₄
List the strong bases (In the order from the ppt)
1. LiOH 2. NaOH 3. KOH 4. RbOH 5. CsOH 6. Ca(OH)₂ 7. Sr(OH)₂ 8. Ba(OH)₂
Which of the following substances will form acidic aqueous solutions? 1. NH₄Cl 2. K₂CO₃ 3. Cu(NO₃)₂ 4. NaF
1. and 3.
What are the two factors that influence ionization
1. the strength of the bond 2. The polarity of the bond
State Function
A quantity that does not depend on the process by which the system was prepared
Entropy
A thermodynamic parameter (S) that is a measure of the disorder or randomness in a system
What is the pH of 1.3 x 10⁻³ aqueous sodium hydroxide solution? A. 11.1 B. 8.3 C. 7.9 D. 2.9 E. None of the above answers are correct
A.
Which of the following is not true for the dissociation of a strong acid? A. The equilibrium lies far to the left B. Ka is large C. The conjugate base will be weak D. The equilibrium lies far to the right E. [H+] > [HA]
A.
Which of the following reactions is (are) spontaneous? A. CH₄(g) + 2O₂(g) → CO₂(g) + H₂O(g) B. CO₂(g) → C(s) + O₂(g) C. 2Fe₂O₃(s) → 4Fe(s) + 3O₂(g)
A.
Which of the following statements about the molecular basis of entropy is false? A. Adding heat decreases entropy B. Entropy depends on the substance's state C. Entropy increases as no. of atoms in a molecule increases D. Entropy is an extensive property: more moles, more entropy E. Entropy is a state function
A.
Identify the strong acid: A. H₂O B. HClO₄ C. HCO₃⁻ D. HF E. HCN
B.
If the following salts were dissolved in water at equal concentration, which solution would have the highest pH? A. NaCl B. NaClO C. NaClO₂ D. NaClO₃ E. NaClO₄
B.
Milk of magnesia has a pH = 10.4. What is its [OH⁻] ? A. 1.0 x 10⁻⁴ M B. 2.5 x 10⁻⁴ M C. 4.0 x 10⁻¹¹ M D. 3.6 M E. 1.0 x 10⁻¹¹ M
B.
Rhubarb leaves contain about 5% oxalic acid by weight, which is a compound that can cause kidney failure. Oxalic acid has a formula of H₂C₂O₄, a Ka1 of 1.5 x 10⁻³, and a Ka2 of 6.4 x 10⁻³. Which reaction below corresponds to the equilibrium constant Ka1? A. H₂C₂O₄ ⇌ 2 H⁺ + C₂O₄²⁻ B. H₂C₂O₄ + H₂O ⇌ HC₂O₄⁻ + H₃O⁺ C. H₂C₂O₄ ⇌ HC₂O₄⁻ + H⁺ D. HC₂O₄⁻ + H₂O ⇌ C₂O₄²⁻ + H₃O⁺ E. HC₂O₄⁻+ H₂O ⇌ H₂C₂O₄²⁻ + OH⁻
B.
Strong acids are characterized as which of the following? 1. weak electrolytes 2. having spectator ions as conjugate bases 3. having very large K values A. 1 and 2 B. 2 and 3 C. 1, 2 and 3 D. 1 and 3 E. 1 only
B.
The hydrogen halides are all polar molecules which form acidic solutions. Which of the following is the weakest acid? A. HBr B. HF C. HCl D. HI
B.
The spontaneity of a reaction depends on all of the following except: A. Temperature B. Equilibrium Constant K C. Enthalpy D. Entropy
B.
What is the pH of 0.1 M Ca(NO₂)₂? (Ka for HNO₂ = 4.5 x 10⁻⁴) A. 12 B. 8.3 C. 7.5 D. 2.7 E. 9.3
B.
Which of the following is not a Law of Thermodynamics? A. The total energy in the universe is constant B. The number of microstates tends to increase with temperature C. The total entropy in the universe is increasing D. The entropy of every pure crystalline substance at 0K is zero
B.
Which of the following is the strongest acid? A. F₃C-COOH B. Cl₃C-COOH C. Br₃C-COOH D. Br₂ClC-COOH E. H₃C-COOH
B.
Which of the following species cannot act as a Lewis base? A. Cl⁻ B. CH₄ C. OH₂ D. OH⁻ E. NH₃
B.
Which of the following species will not undergo water hydrolysis? A. F⁻ B. NO₃⁻ C. S²⁻ D. (CH₃)NH₂ E. CH₃COO⁻
B.
Which of the following statements about spontaneous reactions is false? A. Spontaneous reactions may be slow B. Saying a reaction is spontaneous is the same as saying the reaction will occur if the reactants are mixed C. A nonspontaneous reaction cannot occur unless there is outside intervention D. If we know that the reaction is nonspontaneous, there is no point in mixing the reactants E. Useful work can be extracted from a spontaneous process
B.
Which of the following will give the most basic solution when dissolved in water (highest pH)? A. NaClO₄ B. NaIO C. NaBrO D. NaClO E. NaCl
B.
The conjugate acid and conjugate base of bicarbonate ion, HCO₃⁻, are, respectively: A. H₃O⁺ and OH⁻ B. H₃O⁺ and CO₃²⁻ C. H₂CO₃ and OH⁻ D. H₂CO₃ and CO₃²⁻ E. CO₃²⁻ and OH⁻
D.
The entropy of which of the following systems increases? i. An ice cube melts ii. Water vapor condenses iii. Dry ice sublimes A. i only B. ii only C. i, ii, and iii D. i and iii only E. i and ii only
D.
Which species is the conjugate base in the following reaction? HCl(aq) + H₂O(l) ⇌ H₃O+(aq) + Cl-(aq)
Cl-(aq)
A demonstration done in lecture illustrated acid-base properties of oxides and hydroxides. Which of the following elements forms an oxide that produces an acidic solution in water? A. Ca B. Mg C. Ba D. P E. He
D.
Dr. Todd needs to buffer a solution at pH = 7.4, so that he can use it in his study of red blood cells in a patient with an internal injury. Which of the following choices would be best to use in his study? A. NaCl / HCL (Ka>1) B. NaCN / HCN (Ka = 4.9 x 10⁻¹⁰) C. NaC₂H₃O₂ / HC₂H₃O₂ (Ka = 1.8 x 10⁻⁵) D. Na₂HPO₄ / NaH₂PO₄ (Ka₂ = 6.2 x 10⁻⁸) E. NaClO₂ / HClO₂ (Ka = 1.1 x 10⁻²)
D.
Which of the following is most likely to act as a Lewis base? A. Fe²⁺ B. CCl₄ C. BF₃ D. Cr²⁺ E. NH₃
E.
Which species is the conjugate base of H₂AsO₄⁻? A. OH⁻ B. H₃AsO₄ C. H₃O⁺ D. AsO₄³⁻ E. HAsO₄²⁻
E.
Thermodynamics
Explores the connection between energy and the EXTENT of a reaction but tells you nothing about reaction rates
T/F: A solution of a salt in which the anion is the conjugate base of a weak acid will be acidic
False
T/F: A spontaneous reaction always happens very quickly
False
T/F: A spontaneous reaction is always endothermic
False
T/F: A spontaneous reaction is always exothermic
False
T/F: A spontaneous reaction is spontaneous at all temperatures
False
T/F: Entropy decreases as the number of microstates of the system increases
False
T/F: For carboxylic acids, the strength of the acid does not depend on the nature of the R group
False
T/F: For weak acids, [H⁺] final = [HX] initial
False
T/F: Most acids are strong acids
False
T/F: Processes that are spontaneous at one temperature will also be spontaneous at other temperatures
False
T/F: Strong acids are weak electrolytes
False
T/F: The acidity of an aqueous solution depends on the concentration of hydroxide ions [OH-]
False
T/F: The titration of a strong acid with a strong base often results in buffer solutions
False
T/F: Thermodynamics can explain reaction rates
False
T/F: Weak acids are strong electrolytes
False
T/F: When [H₃O+] > [OH-], the solution is basic
False
Which species is the base in the following reaction? NH₃(aq) + H₂O(l) ⇌ NH₄+(aq) + OH-(aq)
NH₃(aq)
Which species is the conjugate acid in the following reaction? NH₃(aq) + H₂O(l) ⇌ NH₄+(aq) + OH-(aq)
NH₄+(aq)
Which species is the conjugate base in the following reaction? NH₃(aq) + H₂O(l) ⇌ NH₄+(aq) + OH-(aq)
OH-(aq)
Spontaneous processes
One that is capable of proceeding in the forward direction to a substantial extent under a given set of conditions
Which salt (or salts) will form a basic aqueous solution? 1. KCl 2. CsF 3. KCN 4. NH₄Cl
both 2 and 3
Acid metal ions generally hav a ____ ionic radius and a ____ charge a) small, high negative b) large, low positive c) small, high positive d) large, low negative e) small, low positive
c)
The conjugate of a weak acid is a) a spectator ion b) water c) weak base d) strong base
c)
What is a Bronsted Acid? a) Any compound capable of accepting a H+ ion b) Any compound that releases OH- when dissolved in H₂O c) Any compound capable of donating a H+ ion d) Any compound that releases H+ when dissolved in H₂O
c)
When K_b = K_a, the solution is a) acidic b) basic c) neutral
c)
Which of the following elements has the greatest electronegativity? a) Al b) P c) N d) B e) Na
c)
Which of the following is NOT likely to be a Lewis acid? a) Cr³⁺ b) BF₃ c) CF₄ d) Na⁺ e) H⁺
c)
Which of the following is NOT likely to be a Lewis acid? a) Fe³⁺ b) BF₃ c) CH₄ d) Be²⁺ e) Ca²⁺
c)
Which of these is not a physical property of acids? a) sour taste b) dissolves active metals, usually liberating H₂ c) turns litmus paper blue d) corrosive
c)
Put the following in order of increasing acidity SO₂, GeO₂, CaO, Cl₂O₇ a) SO₂ < GeO₂ < CaO < Cl₂O₇ b) CaO < SO₂ < GeO₂ < Cl₂O₇ c) Cl₂O₇ < GeO₂ < CaO < SO₂ d) Cl₂O₇ < SO₂ < GeO₂ < CaO e) CaO < GeO₂ < SO₂ < Cl₂O₇
e)
Which of the following compounds produces an acidic solution when dissolved in water? a) Na₂O b) KO₂ c) MgO d) CaO e) CO₂
e)
Which of the following is not a metal? a) Li b) La c) Mg d) Cs e) Se
e)
Arrange the following acids in order of decreasing acidity: HNO₂, HClO, HBrO, HIO₄ a) HIO₄ > HNO₂ > HBrO > HClO b) HIO₄ > HClO > HBrO > HNO₂ c) HClO > HBrO > HNO₂ > HIO₄ d) HBrO > HClO > HNO₂ > HIO₄ e) HBrO > HClO > HIO₄ > HNO₂ f) HIO₄ > HNO₂ > HClO > HBrO
f)