CHEM EXAM 3
Which of the following is a a (conjugate base, conjugate acid) pair?
(CN-, HCN)
Kp=0.0599, Kp=0.0324, Kp=0.0621 (equilibrium)
3
State whether C6H5NH2 is a strong or weak base
weak
State whether CH3NH2 is a strong or weak base
weak
State whether HC2H3O2 is a strong or weak acid
weak
Which of the following is a (conjugate acid, conjugate base) pair?
(H2O, OH-)
What is the pH of a 2.4x10^-4 M aqueous solution of Ba(OH)2? (note: due to the significant digits required in the answer-
2.4x10^-4 times 2/1= 4.8x10^-4 14.00+log(4.8x10^-4)=answer
Which of the following is the conjugate BASE of HSO4-?
SO4^2-
At equilibrium, the rate of formation of products is equal to the rate of formation of reactants.
True
Once a reaction reaches equilibrium, the concentrations of reactants and products remain constant.
True
Which of the following describes the effect of cooling a reaction mixture at equilibrium, if the forward reaction is endothermic? (Keq is the equilibrium constant)
decrease in Keq; reaction shifts to the left
State whether NH3 is a strong or weak base
weak
Mg(OH)2 is insoluble in water, which means that the equilibrium constant forMg(OH)2(s) = Mg2+(aq) + 2 OH-(aq)is a very small number. To dissolve Mg(OH)2, we need to shift the equilibrium to the right. Can this be done by adding EDTA4-, which reacts with Mg2+ to form Mg(EDTA)22-?
yes
Mg(OH)2 is insoluble in water, which means that the equilibrium constant forMg(OH)2(s) = Mg2+(aq) + 2 OH-(aq)is a very small number. To dissolve Mg(OH)2, we need to shift the equilibrium to the right. Can this be done by adding HCl(aq)?
yes
NO2(g) has a reddish color. N2O4(g) is colorless. In an equilibrium mixture of these two gases, the following reaction occurs:2 NO2(g)= N2O4(g)When a reddish-colored sample of this mixture is cooled, the color fades. From this observation, can we conclude that Keq for the reaction decreases as the temperature increases?
yes
NO2(g) has a reddish color. N2O4(g) is colorless. In an equilibrium mixture of these two gases, the following reaction occurs:2 NO2(g)= N2O4(g)When a reddish-colored sample of this mixture is cooled, the color fades. From this observation, can we conclude that heating favors the forward reaction vs. the reverse the reaction?
yes
NO2(g) has a reddish color. N2O4(g) is colorless. In an equilibrium mixture of these two gases, the following reaction occurs:2 NO2(g)= N2O4(g)When a reddish-colored sample of this mixture is cooled, the color fades. From this observation, can we conclude that the reverse reaction is endothermic?
yes
Consider the following reaction:2 NH3(g) N2(g) + 3 H2(g)If a vessel contains only 0.139 atm of pure NH3 initially and, at equilibrium the pressure of N2 was found to be x atm, we can calculate the equilibrium constant Kp using
(x)(3x)3 / (0.139 - 2x)2
what is the pH of a 3.8x10^-3 M aqueous solution of HNO3? (same with HBr)
-log(3.8x10^-3)
What is the pH of a solution where [H3O+]=4.7x10^-5
-log10(4.7x10^-5)=answer
What is the pOH solution of where [OH-]=5.1x10^-2
-log10(5.1x10^-2)=answer
Consider the following representation of a fictitious reaction. Which of the following is/are true?
1, 111, and 1V only
What is the [H3O+] in a solution where [OH-] is 2.00x10^-7?
1.00x10^-14 divided by 2.00x10^-7= answer
What is the [OH-] in a solution where [H3O+] is 3.80x10^-9?
1.00x10^-14 divided by 3.80x10^-9= answer
What is the concentration of OH-in a 1.20x10^-3 M aqueous solution of Ca(OH)2?
1.20x10^-3 times 2/1 = answer
What is the concentration of H3O+ in a 1.20x10^-5 M Aqueous solution of HCLO4?
1.20x10^-5 (same number)
What is the concentration of OH- in a 1.48x10^-4 M aqueous solution of NaOH?
1.48x10^-4 times 1/1 = answer
What is the [H3O+] in a solution with a pH of 7.82?
10^-7.82=answer
Which of the following is/are true about a reaction mixture at equilibrium?
111 and 1V only
What is the pH of a solution where [OH-]=1.1x10^-10
14.00 + log(1.1x10^-10)=answer
What is the [OH-] in a solution with a pH of 4.08?
14.00-4.08=9.92 10^-9.92= answer
K=8.00x10^-12 K=1.70x10^7
4.32E-4
What is the pH of a 6.3x10^-1 M aqueous solution of KOH?
6.3x10^-1 times 1/1=answer
Which of the following is the Arrhenius definition of an acid?
A substance that yields H+ or H3O+ in water
Which of the following is the Arrhenius definition of a base?
A substance that yields OH- in water
For the following pair of acids: Acid 1: H2CO3 Acid 2: HCO3- which is the stronger acid?
Acid 1
For the following pair of acids: Acid 1: H2S Acid 2: H20 Which is the stronger acid?
Acid 1
For the following pair of acids: Acid 1: H2SO3 Acid 2: H2SeO3 Which is the stronger
Acid 1
For the following pair of acids: Acid 1: H2SO4 Acid 2: H2SO3 Which is the stronger acid?
Acid 1
For the following pair of acids: Acid 1: H3PO4 Acid 2: H3AsO4 Which is the stronger acid?
Acid 1
For the following pair of acids: Acid 1: H3PO4 Acid 2: H3PO3 Which is the stronger acid?
Acid 1
For the following pair of acids: Acid 1: HF Acid 2: H2O Which is the stronger acid?
Acid 1
For the following pair of acids: Acid 1: HI Acid 2: HBr which is the stronger acid?
Acid 1
For the following pair of acids: Acid 1: H2S Acid 2: HS- Which is the stronger acid?
Acid 1
For the following pair of acids: Acid 1: HBr Acid 2: H2Se Which is the stronger acid?
Acid 1
For the following pair of acids: Acid 1: H2S Acid 2: H2Te Which is the stronger acid?
Acid 2
For the following pair of acids: Acid 1: H2S Acid 2: HCL Which is the stronger acid?
Acid 2
For the following pair of acids: Acid 1: H2Te Acid 2:HI Which is the stronger acid?
Acid 2
For the following pair of acids: Acid 1: HBrO4 Acid 2: HCLO4 Which is the stronger acid?
Acid 2
For the following pair of acids: Acid 1: HCLO Acid 2: HCLO2 Which is the stronger acid?
Acid 2
For the following pair of acids: Acid 1: HF Acid 2: HCL Which is the stronger acid?
Acid 2
For the following pair of acids: Acid 1: HIO Acid 2: HCLO Which is the stronger acid?
Acid 2
For the following pair of acids: Acid 1: HNO2 Acid 2: HNO3 Which is the stronger acid?
Acid 2
For the following pair of acids: Acid 1: HPO4^2- Acid 2: H2PO4- Which is the stronger acid?
Acid 2
For the following pair of acids: Acid 1: HSO4- Acid 2: H2SO4 Which is the stronger acid?
Acid 2
Which of the following is the conjugate BASE of HCO3-?
CO3^2-
Which of the following describes the effect of ADDING REACTANTS to a reaction mixture at equilibrium? (Q is the reaction quotient, Keq is the equilibrium constant)
Decrease in Q; reaction shifts to the right until Q=Keq again
Which of the following describes the effect of REMOVING PRODUCTS to a reaction mixture at equilibrium? (Q is the reaction quotient, Keq is the equilibrium constant)
Decrease in Q; reaction shifts to the right until Q=Keq again
At equilibrium, all atomic and molecular motions cease to occur in the system.
False
True or False. Once a reaction reaches equilibrium, there is no further transformation of reactant molecules into product molecules.
False
Which of the following is the conjugate ACID of HCO3-?
H2CO3
Which of the following is the conjugate ACID of HSO4-?
H2SO4
Which of the following is the conjugate ACID of CO3^2-?
HCO3-
Which of the following is the conjugate BASE of H2CO3?
HCO3-
Which of the following is a conjugate ACID of SO4^2-?
HSO4-
Which of the following is the conjugate BASE of H2SO4?
HSO4-
Which of the following describes the effect of REMOVING REACTANTS to a reaction mixture at equilibrium? (Q is the reaction quotient, Keq is the equilibrium constant)
Increase in Q; reaction shifts to the left until Q=keq again
A student is studying the equilibrium represented by the equation: 2CrO42-(aq, yellow) + 2 H3O+(aq) = Cr2O72-(aq, orange) + 3H2O(l) The equilibrium mixture is yellow in color.What direction will the equilibrium shift and what color should the mixture be after adding Na2CrO4(s) to the equilibrium mixture?
Na2CrO4(s): right; more orange HCl: right; more orange KOH(s): left; more orange NaOH(s): left; more yellow H2SO4: right; more orange
When a reaction reaches equilibrium, the forward and reverse reactions are occurring at the same rate.
True
Consider the following fictitious reaction at equilibrium: A(g)+B(g)--->C(g) deltaH=-80KJ Which of the following stresses would NOT SHIFT the equilibrium?
adding a catalyst & increasing the volume by decreasing the pressure at constant temperature & adding more A
Which of the following is the lewis definition of an acid?
an ion or molecule that accepts a pair of electrons as it forms a coordinate covalent bond with another ion or molecule
Which of the following is the Bronsted-Lowry definition of a base?
an ion or molecule that accepts a proton
Which of the following is the Lewis definition of a base?
an ion or molecule that donates a pair of electrons as it forms a coordinate covalent bond with another ion or molecule
Which of the following is the Bronsted-Lowry definition of an acid?
an ion or molecule that donates a proton to another ion or molecule
Consider the following reaction: NH4+(aq) + H2O(l) --> NH3(aq) + H3O+(aq) Which occurs when ammonium chloride (NH4Cl) is dissolved in water. The Bronsted-Lowry base/acid for the forward/reverse reaction is
base/forward= H2O acid/forward= NH4+ base/reverse= NH3 acid/reverse= H3O+
Consider the following reaction: CN-(aq) + H2O(l) --> HCN(aq) + OH-(aq) Which occurs when potassium cyanide (KCN) is dissolved in water. The Bronsted-Lowry base/acid for the forward/reverse reaction is
base/forward=CN- acid/forward=H2O base/reverse=OH- acid/reverse=HCN
Which of the following describes the effect of cooling a reaction mixture at equilibrium, if the reverse reaction is exothermic? (Keq is the equilibrium constant)
decrease in Keq; reaction shifts to the left
Which of the following describes the effect of heating a reaction mixture at equilibrium, if the forward reaction is exothermic? (Keq is the equilibrium constant)
decrease in Keq; reaction shifts to the left
Which of the following describes the effect of heating a reaction mixture at equilibrium, if the reverse reaction is endothermic? (Keq is the equilibrium constant)
decrease in Keq; reaction shifts to the left
Consider the following fictitious reaction at equilibrium: A(g)+B(g)--->C(g) deltaH=-80KJ Which of the following stresses would shift the equilibrium to the RIGHT?
decreasing the temperature &
Which of the following describes the effect of cooling a reaction mixture at equilibrium, if the forward reaction is exothermic? (Keq is the equilibrium constant)
increase in Keq; reaction shifts to the right
Which of the following describes the effect of cooling a reaction mixture at equilibrium, if the reverse reaction is endothermic? (Keq is the equilibrium constant)
increase in Keq; reaction shifts to the right
Which of the following describes the effect of heating a reaction mixture at equilibrium, if the forward reaction is endothermic? (Keq is the equilibrium constant)
increase in Keq; reaction shifts to the right
Which of the following describes the effect of heating a reaction mixture at equilibrium, if the reverse reaction is exothermic? (Keq is the equilibrium constant)
increase in Keq; reaction shifts to the right
Which of the following describes the effect of ADDING PRODUCTS to a reaction mixture at equilibrium? (Q is the reaction quotient, Keq is the equilibrium constant)
increase in Q; reaction shifts to the left until Q=Keq again
Consider the following fictitious reaction at equilibrium: A(g)+B(g)--->C(g) deltaH=+25KJ Which of the following stresses would shift the equilibrium to the LEFT?
increasing the temperature
Consider the following fictitious reaction at equilibrium: A(g)+B(g)--->C(g) deltaH=-80KJ Which of the following stresses would shift the equilibrium to the LEFT?
increasing the temperature & Adding more C
A student is studying the equilibrium represented by the equation: [Cu(H2O)6]2+(aq, blue) + 5Br-(aq) = CuBr42-(aq, green) + 6H2O(l) The equilibrium mixture is blue in color.What direction will the equilibrium shift and what color should the mixture be after adding AgNO3, which reacts with Br- to form AgBr(s), to the equilibrium mixture?
left; more blue
Mg(OH)2 is insoluble in water, which means that the equilibrium constant forMg(OH)2(s) = Mg2+(aq) + 2 OH-(aq)is a very small number. To dissolve Mg(OH)2, we need to shift the equilibrium to the right. Can this be done by adding MgCl2(aq)?
no
Mg(OH)2 is insoluble in water, which means that the equilibrium constant forMg(OH)2(s) = Mg2+(aq) + 2 OH-(aq)is a very small number. To dissolve Mg(OH)2, we need to shift the equilibrium to the right. Can this be done by adding NaOH(aq)?
no
NO2(g) has a reddish color. N2O4(g) is colorless. In an equilibrium mixture of these two gases, the following reaction occurs:2 NO2(g)= N2O4(g)When a reddish-colored sample of this mixture is cooled, the color fades. From this observation, can we conclude that Keq for the reaction decreases as the temperature decreases?
no
NO2(g) has a reddish color. N2O4(g) is colorless. In an equilibrium mixture of these two gases, the following reaction occurs:2 NO2(g)= N2O4(g)When a reddish-colored sample of this mixture is cooled, the color fades. From this observation, can we conclude that Keq for the reaction increases as the temperature increases?
no
NO2(g) has a reddish color. N2O4(g) is colorless. In an equilibrium mixture of these two gases, the following reaction occurs:2 NO2(g)= N2O4(g)When a reddish-colored sample of this mixture is cooled, the color fades. From this observation, can we conclude that the forward reaction is endothermic?
no
NO2(g) has a reddish color. N2O4(g) is colorless. In an equilibrium mixture of these two gases, the following reaction occurs:2 NO2(g)= N2O4(g)When a reddish-colored sample of this mixture is cooled, the color fades. From this observation, can we conclude that the reverse reaction is exothermic?
no
[Cu(H2O)6]2+(aq, blue) + 5Br-(aq) = CuBr42-(aq, green) + 6H2O(l) the equilibrium mixture is blue in color The student draws some of the blue solution into the bulb of a Beral pipet. The pipet is placed, bulb down, in a hot-water bath. After a short time, the solution changes from blue to green. From these observations can we conclude that the forward reaction is exothermic?
no
[Cu(H2O)6]2+(aq, blue) + 5Br-(aq) = CuBr42-(aq, green) + 6H2O(l) the equilibrium mixture is blue in color The student draws some of the blue solution into the bulb of a Beral pipet. The pipet is placed, bulb down, in a hot-water bath. After a short time, the solution changes from blue to green. From these observations can we conclude that the reverse reaction is endothermic?
no
A student is studying the equilibrium represented by the equation: [Cu(H2O)6]2+(aq, blue) + 5Br-(aq) = CuBr42-(aq, green) + 6H2O(l) The equilibrium mixture is blue in color.What direction will the equilibrium shift and what color should the mixture be after adding NaBr(s) to the equilibrium mixture?
right; more green
Consider a hypothetical acid-base indicator, "HX", ionizes in water according to the equationHX(aq) = H+(aq) + X-(aq)Suppose HX(aq) is red and X- is yellow. How would an equilibrium mixture behave if we were to add concentrated H2SO4?
shift left; more red
Consider a hypothetical acid-base indicator, "HX", ionizes in water according to the equationHX(aq) = H+(aq) + X-(aq)Suppose HX(aq) is red and X- is yellow. How would an equilibrium mixture behave if we were to add concentrated HCl?
shift left; more red
Consider a hypothetical acid-base indicator, "HX", ionizes in water according to the equationHX(aq) = H+(aq) + X-(aq)Suppose HX(aq) is red and X- is yellow. How would an equilibrium mixture behave if we were to add KOH(aq)?
shift right; more yellow
Consider a hypothetical acid-base indicator, "HX", ionizes in water according to the equationHX(aq) = H+(aq) + X-(aq)Suppose HX(aq) is red and X- is yellow. How would an equilibrium mixture behave if we were to add NaOH(aq)?
shift right; more yellow
State whether Ba(OH)2 is a strong or weak base
strong
State whether H2SO4 is a strong or weak acid
strong
State whether HBr is a stong or weak acid
strong
State whether HCL is a strong or weak acid
strong
State whether HI is a strong or weak acid
strong
State whether HNO3 is a strong or weak acid
strong
State whether KOH is a strong or weak base
strong
State whether LiOH is a strong or weak base
strong
State whether NaOH is a strong or weak base
strong
A reaction has reached equilibrium and the concentration of reactant "X" was found to be 2.22x10^-5 mol/L. If the system is left undisturbed, we expect
the concentration of X to remain at 2.22x10^-5 mol/L
Consider the hypothetical reaction: Consider the hypothetical reaction: A(s) = B(aq) + 2 C(aq)If at a given instant, the concentrations of B and C are 2.18x10-8 and 0.217 mol/L, and the equilibrium constant (Keq) is 4.14x10-23, thenant, the concentrations of B and C are 2.18x10-8 and 0.217 mol/L, and the equilibrium constant (Keq) is 4.14x10-23, then
the reaction quotient Q is larger than Keq and we expect formation of more A(s) until Q=Keq
Consider the hypothetical reaction: A(s)= B(aq) + 2 C(aq) If at a given instant, the concentrations of B and C are 2.15x10^-8 and 0.239mol/L, and the equilibrium constant (Keq) is 3.98x10^-23, then
the reaction quotient Q is larger than Keq and we expect formation of more A(s) until Q=Keq
Consider the hypothetical reaction: A(s)= B(aq) + 2 C(aq) If at a given instant, the concentrations of B and C are 4.10x10^-8 and 3.88x10^-8 mol/L, and the equilibrium constant (Keq) is 2.76x10^-22
the reaction quotient Q is smaller than Keq and we expect formation of more B(aq) and C(aq) until Q=Keq
True or False. At equilibrium, the rate of formation of products is equal to the rate of formation of reactants.
true
True or False. Once a reaction reaches equilibrium, the concentrations of reactants and products remain constant.
true
State whether HCN is a strong acid or weak acid
weak
State whether HF is a strong acid or weak acid
weak
State whether HNO2 is a strong acid or a weak acid
weak
State whether NO2- is a strong or weak base
weak
[Cu(H2O)6]2+(aq, blue) + 5Br-(aq) = CuBr42-(aq, green) + 6H2O(l) the equilibrium mixture is blue in color The student draws some of the blue solution into the bulb of a Beral pipet. The pipet is placed, bulb down, in a hot-water bath. After a short time, the solution changes from blue to green. From these observations can we conclude that Keq for the reaction increases as the temperature increases?
yes
[Cu(H2O)6]2+(aq, blue) + 5Br-(aq) = CuBr42-(aq, green) + 6H2O(l) the equilibrium mixture is blue in color The student draws some of the blue solution into the bulb of a Beral pipet. The pipet is placed, bulb down, in a hot-water bath. After a short time, the solution changes from blue to green. From these observations can we conclude that Keq for the reaction decreases as the temperature decreases?
yes
[Cu(H2O)6]2+(aq, blue) + 5Br-(aq) = CuBr42-(aq, green) + 6H2O(l) the equilibrium mixture is blue in color The student draws some of the blue solution into the bulb of a Beral pipet. The pipet is placed, bulb down, in a hot-water bath. After a short time, the solution changes from blue to green. From these observations can we conclude that the forward reaction is endothermic?
yes
[Cu(H2O)6]2+(aq, blue) + 5Br-(aq) = CuBr42-(aq, green) + 6H2O(l) the equilibrium mixture is blue in color The student draws some of the blue solution into the bulb of a Beral pipet. The pipet is placed, bulb down, in a hot-water bath. After a short time, the solution changes from blue to green. From these observations can we conclude that the reverse reaction is exothermic?
yes
