Deck 7: Chemical Equilibrium

Question 1

When the direction for a reaction is reversed the new value of K is:

A)K' = log(K).
B)K' = ln(K).
C)K' = 10^K.
D)K' = 1/K.
E)K'= e^K.

Answer 1

K' = 1/K.

Question 2

In which solution is solubility of silver chloride the largest?

A)Pure water
B)0)05 M CaCl₂
C)0)10 M NaCl
D)0)10 M FeCl₃
E)0)15 M AgNO₃

Answer 2

Pure water

Question 3

For the reaction aA (aq)+ bB (s) $\leftrightarrow$ cC (l)+ dD (g),all of the statements below are TRUE,except:

A)
B)concentrations of solutes are expressed in moles per liter.
C)concentrations of gases are expressed in bars.
D)concentrations of pure solids,pure liquids and solvents are omitted because they are negligible.
E)quantities in the equilibrium expression are the ratio of the concentration of the species to the concentration in its standard state.

Answer 3

concentrations of pure solids,pure liquids and solvents are omitted because they are negligible.

Question 4

Nickel forms three complexes with hydroxide,NiOH⁺ (aq),Ni(OH)₂ (aq)and Ni(OH (aq).Which statement(s)regarding the impact of complex formation on the solubility of nickel hydroxide are FALSE?
I Hydroxide behaves as a Lewis acid when forming a complex with nickel.
II The total nickel concentration is [Ni²⁺]_tot = [Ni²⁺] + [NiOH⁺] + [Ni(OH)₂] + [Ni(OH].
III As [OH^-] increases,the solubility of Ni(OH)₂ initially decreases but then increases.
IV

A)Only I
B)II and III
C)Only III
D)Only IV
E)I,II,III,and IV

Question 5

The molar solubility of a saturated iron(II)carbonate solution derived from the K_sp value is 5.6 x 10⁻⁶ M.The molar solubility is greater than 5.6 x 10⁻⁶ M when accounting for additional reactions.Which of the reactions below will not increase the solubility of iron(II)carbonate?

A)Fe²⁺ (aq)+ OH⁻ (aq) $\leftrightarrow$ FeOH⁺ (aq)
B)CO₃²⁻ (aq)+ H⁺ (aq) $\leftrightarrow$ HCO₃⁻ (aq)
C)HCO₃⁻ (aq)+ H⁺ (aq) $\leftrightarrow$ H₂ CO₃ (aq)
D)H₂CO₃ (aq) $\leftrightarrow$ CO₂ (g)+ H₂O (l)
E)FeOH⁺ (aq)+ OH⁻ $\leftrightarrow$ Fe(OH)₂ (s)

Question 6

All of the following are strong acids,except:

A)HCl.
B)HNO_3.
C)HBr.
D)HClO_4.
E)HF.

Question 7

A student attempts to separate Cl⁻ and I⁻ from a solution that is 0.05 M Cl⁻ and 0.10 M I⁻ with Pb(NO₃)₂.As Pb(NO₃)₂ is added,which anion will precipitate first and what will the concentration of the anion be when the second anion begins to precipitate? K_sp = 1.7 x 10⁻⁵ for PbCl₂ and K_sp = 9.8 x 10⁻⁹ for PbI₂.

A)iodide precipitates first;0.0068 M iodide
B)iodide precipitates first;0.0012 M iodide
C)iodide precipitates first;0.05 M iodide
D)chloride precipitates first;0.0012 chloride
E)chloride precipitates first;0.10 M chloride

Question 8

For a reaction with a H^o = +50 kJ and a $\Delta$ S^o = +100.0 J/K, $\Delta$ G^o is____________________ and the equilibrium constant is____________________ .

A)negative;less than 1
B)negative;greater than 1
C)positive;less than 1
D)positive;greater than 1
E)zero;1

Question 9

For the reaction HCN (aq)+ H₂O (l) $\leftrightarrow$ CN^- (aq)+ H₃O⁺ (aq),all of the following will shift the equilibrium toward the products,except:
I adding HCN.
II adding H₂O.
III removing CN⁻.
IV removing H₃O⁺.

A)I
B)II
C)I,III,and IV
D)II and IV
E)III

Question 10

The pH of a solution is 9.65.The solution is________________________________________and the hydroxide concentration is____________________ than the hydronium concentration.

A)acidic;less
B)acidic;greater
C)neutral;equal
D)basic;________________________________________greater
E)basic;less

Question 11

Which of the following is INCORRECT for Brønsted-Lowry acids and bases?

A)Acids are proton donors.
B)NH₄⁺ is the conjugate acid of the weak base NH₃.
C)When an acid and a base react,the acid and base neutralize each other and form a salt.
D)Water reacts with itself to form hydronium and hydroxide,a process called autoprotolysis.
E)CH₃CN is a protic solvent.

Question 12

What is the pH for a 5 x 10⁻⁵ M OH⁻ solution?

A)5)70
B)4)30
C)9)70
D)5)00
E)9)00

Question 13

Which statements below are TRUE for enthalpy and entropy?
I Enthalpy is the heat flow,q,under constant applied pressure.
II Standard conditions for entropy and enthalpy changes are 1 M concentration,1 bar pressure and 298.15 K.
III The entropy change for a system is the amount of energy,at a given temperature,that is dispersed into motion of the molecules in the system.
IV When the value of $\Delta$ H is negative,heat is released.When the value of $\Delta$ S is negative,entropy is increased.

A)I,II and III
B)I,III and IV
C)II and IV
D)III and IV
E)Another combination is true.

Question 14

Calculate the total nickel concentration for a solution prepared by dissolving Ni(OH)₂ (s)in a 0.10 M OH⁻ solution.K_sp = 6 × 10⁻¹⁶, $\beta$ ₁ = 1.26 × 10⁴, $\beta$ ₂ = 1 × 10⁹,and $\beta$ ₃ = 1 × 10¹²_.

Question 15

Calculate the molar solubility for calcium fluoride in a 0.10 M NaF solution.K_sp = 3.2 × 10⁻¹¹ for CaF₂.

Question 16

Silver ion is being considered as a reagent for separating IO₃⁻ from CO₃²⁻ in a solution that is 0.060 M in K₂CO₃ and 0.070 M in NaIO₃.Which anion will precipitate first and what will its concentration be when the second anion begins to precipitate? Can the two ions be separated with 99.99% efficiency?
K_sp = 3.1 x 10⁻⁸ for AgIO₃
K_sp = 8.1 x 10⁻¹² for Ag₂CO₃

Question 17

Which of the classes of acids and bases and strength have been incorrectly matched?

A)RCO₂H: weak acid
B)R₃N: weak base
C)RCO₂⁻: weak base
D)R₃NH⁺: weak acid
E)R₄NOH: weak base

Question 18

For a triprotic acid,which of the following is NOT true?

A)K_a1K_b3=K_w
B)
C)K_a1K_b2=K_w
D)K_a3K_b1=K_w
E)

Question 19

Calculate the pH for a 0.293 M OH⁻ solution.

Question 20

A reaction has a $\Delta$ = −167.5 kJ/mol and $\Delta$ = 57.3 J/mol K.Calculate the equilibrium constant for the reaction.