Module 8
For the reaction at equilibrium,
2SO3- <--> 2SO2-2 + O2 (ΔHorxn = 198 kj/mol)
If the reaction temperature increases, which way will the reaction shift to go back to equilibrium?
Shift right
Name all the strong acids and strong bases.
Strong Acids:
1. Nitric acid (HNO3)
2. Hydrobromic acid (HBr)
3. Hydrochloric acid (HCl)
4. Chloric acid (HClO3)
5. Perchloric acid (HClO4)
6. Hydroiodic acid (HI)
7. Sulfuric acid (H2SO4)
Strong Bases:
1. Sodium hydroxide (NaOH)
2. Lithium hydroxide (LiOH)
3. Potassium hydroxide (KOH)
4. Rubidium hydroxide (RbOH)
5. Cesium hydroxide (CsOH)
6. Strontium hydroxide (Sr(OH)2)
7. Barium hydroxide (Ba(OH)2)
Give both Henderson-Hasselbalch equations.
1. pH = pKa + log([conjugate base]/[acid])
2. pOH = pKb +log([conjugate acid]/[base])
What is only true at the midpoint?
pH = pKa
Originally, Amazon only sold what kind of product?
Books
At a certain temperature, the following reaction comes to equilibrium in a closed container:
N2(g)+3H2(g)⇌2NH3(g)
The equilibrium concentrations are measured as:
[N2]=0.40 M
[H2]=0.60 M
[NH3]=0.20 M
Write the equilibrium expression and solve for the value of equilibrium constant.
1. Kc = [NH3(g)]2 / [N2(g)][H2(g)]3
2. 0.463
Consider the following acid-base reaction:
HCO3-(aq)+H2O(l)⇌H2CO3(aq)+OH-(aq)
Identify the acid, base, conjugate base, and conjugate acid.
HCO3-(aq) - Base
H2O(l) - Acid
H2CO3(aq) - Conjugate acid
OH-(aq) - Conjugate base
Can the following chemical reaction form a buffer system? Why or why not?
CH3COOH(aq) +NaOH(aq) <--> CH₃COONa(aq) +H2O(l)
Yes, since you have a weak reactant (in this case, a weak acid) and its conjugate pair (in this case, a weak conjugate base), you can form a buffer system.
What is the equivalence point equation?
N1V1 = N2V2
What food manufacturing company headquartered in Battle Creek, Michigan, uses several animal mascots to sell its cereals, such as Newton the Owl, Tony the Tiger and a rooster named Cornelius?
The Kellogg Company (Kellogg's)
For the reaction H2(g) + I2(g) <--> 2HI(g), the equilibrium constant, Kc = 50.2 at 445oC.
If the initial concentrations in a reactor at 445ºC are: [H2]0 = [I2]0 = [HI]0 = 1.75x10-3 M, will the concentrations change for the system to come to equilibrium? If concentrations change, which concentrations will increase and which will decrease in order to establish equilibrium? Do not calculate the final, equilibrium concentrations.
Q = 1
1 < 50.2, so Q<K
The reaction isn't in equilibrium
In order to reach equilibrium, the reactant concentrations must increase to shift the reaction to the right.
What is the pH of a solution made by dissolving 0.00500 moles of nitric acid into 250.0 mL of water?
pH = 1.70
You have a buffer solution made by mixing 0.50 M acetic acid and 0.50 M sodium acetate. The pKa of acetic acid is 4.76. What is the pH of this buffer solution?
pH = 4.76
You are titrating 40.0 mL of 0.200 M nitric acid with 20mL of 0.200 M sodium hydroxide. What is the pH of the solution at the equivalence point?
pH = 7
What is Rihanna's real name?
Robyn Fenty
A gas phase reaction takes place in a closed container involving substances A, B, and C as shown below. Initially, [A]0= [B]0= 0.0 M and [C]0= 2.5 M. Write the balanced chemical equation for this process and evaluate (calculate) Keq = Kc showing how you did the calculation.
(Show graph)
A + 3B <--> 2C
Calculate the pH for 0.50 M formic (methanoic) acid. The Ka for formic acid is 1.7x10-4. First give the formula and show the full Lewis structure for formic acid.
1. HCOOH(aq) + H2O(aq) <--> HCOO-(aq) + H3O+(aq)
2. (Show sketch of lewis structure)
3. pH = 2.04
For the two pKa's. pKa1= 6.4 and pKa2= 10.3: State the two mathematical expressions (the equations) by which the two acid equilibrium constants for carbonic acid are defined.
1. H2CO3(aq) + H2O(aq) <--> HCO3-(aq) + H3O+(aq) --pKa=6.4
2. HCO3-(aq) + H2O(aq) <--> CO3-(aq) + H3O+(aq) -- pKa = 10.3
A soluble mixture results when 500.0 mL of 0.30 M sodium acetate is mixed with 500.0 mL of 0.10 M hydrochloric acid. Show how to calculate the pH of the resulting solution and calculate the pH. The Ka for acetic acid is 1.8x10-5.
pH = 5.06
What is the name of the second tallest (standing) bird on the planet? This animal is found only in Australia and is related to the ostrich.
Emu
Suppose 17.0 g of ammonia gas is placed into a previously empty 4.00 L reaction vessel maintained at constant high temperature and the following reaction comes to equilibrium:
2NH3(g) <--> 3H2(g) + N2(g)
Careful measurements show that after equilibrium is established, 0.50 mole of ammonia is present in the reactor.
Sketch reasonable curves for the molar concentrations of the three substances showing the progress of reaction to reach this equilibrium position. Your plot should show linear increments of concentration along the concentration axis.
(Show the sketch)
Calculate the Kb value for the conjugate base of hypochlorous acid if the pKa value is 7.46. Show how you do the calculation. Name this conjugate base.
Kb = 2.88x10-7
Conjugate base - Hypochlorite (ClO-)
The pKa values for sulfurous acid are 1.857 and 7.172.
1. H2SO3-(aq) + H2O(l) <--> HSO3-2(aq) + H3O+(aq) -- pKa = 1.857
HSO3-2(aq) + H2O(l) <--> SO3-3(aq) + H3O+(aq) -- pKa = 7.172
2. Acidic; Since the pKa is smaller, that means that the acid is stronger making it more acidic
If 100mL of 0.30 M sodium hydrogen carbonate is mixed thoroughly with 100mL of 0.10 M sodium hydroxide, show the net reaction (net ionic equation) that takes place and calculate the concentrations of the anions containing carbon atoms in the 200mL of solution. Then solve for the pH. The pKa for carbonic acid is pKa1=6.4 and pKa2= 10.3.
1. [HCO3-] = 0.100M
[CO3-2] = 0.050M
2. pH = 10.0
The Sumatran species of what famously horned mammal officially went extinct in Malaysia in November 2019? The animal is not yet extinct globally, as a few dozen live in Indonesia.
Rhino