pH & pOH
Weak Acid & Base Equilibrium
Acid-Base Reactions
Buffers
pH & pKa
100
If the pH is 8.4, is the compound an acid or base?
Base
100
What is the effect of increasing the concentration of a weak base solution on the H+ ion solution?
The H+ ion concentration decreases.
100
A solution is prepared at 25 degrees celsius in which H30+ is ten times smaller than [OH-] . What is the pH of the solution?
7.50
100
Property of buffers
Resist changes in pH
100
HCOOH(aq) + H2O(l) <-> H3O(aq) + HCOO-(aq)
Ka = 1.8 x 10-4
Write the expression for the equilibrium constant, Ka, for the reaction.
Ka=[H3O][HCOO]/[HCOOH]
200
What is the pH of a 0.0235 M HCl solution?
What is 1.629?
200
At what time do the solutions fully reach equilibrium?
D
200
2H2O(l) <---> H3O+(aq) + OH-(aq)
At 25 degrees Celsius, the autoionization constant for water, Kw, has a value of 1 X 10-14. At 0 degrees Celsius, the value of Kw is less than 1 X 10-14.
What is true of the pOH?
The pOH of pure water at 0 degrees celsius is greater than 7.0.
200
Buffer solutions contain high concentrations of which acid-base conjugate types?
weak acid and it's conjugate base and/or weak base and it's conjugate acid.
200
What is the pH?
9
300
Calculating pH with the hydrogen ion concentration.
pH = -log[H+]
300
_KNO2(aq) + _H2SO4(aq) <-> _K2SO4(aq) + _HNO2(aq)
KNO2 is a ______ base and H2SO4 is a _______ acid.
weak, strong
300
A 60. mL of a sample of 0.10 M HI(aq) is added to 40. mL of 0.20 M KOH(aq).
The pH of the resulting solution is in which range of pH (or decimal approximation)?
12 < x < 13
300
Give the Henderson-Hasselbach Equation.
pH= pKa + log (conjugate base / acid)
300
Calculating pKa without a known pH
pKa = -log(Ka)
400
Calculating pOH with the hydroxide ion concentration
pOH = -log[OH-]
400
_KNO2(aq) + _H2SO4(aq) <-> _K2SO4(aq) + _HNO2(aq)
What numbers, in order, balance this chemical equation?
2,1,1,2
400
CH3COOH(aq) + SO32-(aq) <-> CH3COO-(aq) + HSO3-(aq)
Identify the strongest base in the reaction above.
SO32-
400
Why are buffers important in real-life chemical reactions?
They are able to help maintain stable conditions for safe reactions to occur by handling small changes in pH.
400
Henderson-Hasselbalch Equation
pH = pKa + log([A-]/[HA])
500
What is the pH of a 6.2 x 10-5 M NaOH solution?
What is 9.79?
500
A 0.10 M solution of a weak acid, HA, has a pH of 5.0. What is the value of Ka for the acid?
What is 1 X 10-9?
500
Which of the following is the balanced net ionic equation for the reaction between HF(aq) and KOH(aq)?
HF(aq) + OH-(aq) ---> F-(aq) + H2O(l)
500
Determine the volume, in mL, of 0.100 M NaOH(aq) the student should add to 100 mL of 0.100 M HNO2(aq) to make a buffer solution with a pH of 3.40.
50.0 mL
500
HCOOH(aq) + H2O(l) <-> H3O(aq) + HCOO-(aq)
Ka = 1.8 x 10-4
Calculate the pH of a 0.25 M solution of HCOOH.
2.17