Unit 4 Flashcards
Given one, find the other 3:
Find [OH-], pH, and pOH if there is a 1.0 M solution of CH3COOH and [H+] = 4.2 x 10^-3
Given a concentration, not a pH, so use Kw product constant: Kw = [OH-][H+].
1.00 x 10^-14 = [OH-][4.2 x 10^-3] = 2.4 x 10^-12
pOH = - log [OH-]. = 11.62
pH = pH + pOH. = 2.38
Find the concentration [HCl] if the pOH = 11.819
**strong acid so, [HCl] = [H3O+]
1. pOH + pH = 14.00. = 2.181
2. [H3O+] = 10^-pH. = 0.00659
Find the pH of a 0.025 M KOH solution.
pH = 12.39
1. pOH = -log [OH-]. = 1.602
2. pH + pOH = 14.00. =12.39
Easy: Find the pOH of a solution if the pH = 3.49
pH + pOH = 14.00
pH = 10.51
What is the Kw used for?
What is the pKw?
It is the product of the [H+] concentration and the [H30+] concentration
ONLY AT 25 C, is it [OH-][H3O+] = 1.0 x 10^-14
pKw = pH + pOH
ONLY AT 25 C, is it pH + pOH = 14.00
Find the [Sr(OH)2] of a solution if the pOH = 1.319
[OH-] = 10^-1.319
=0.0480 M
Since Sr(OH)2 –> Sr2+ + 2OH-
the [Sr(OH)2] = 0.0240 M
Find the [NaOH] of a solution if the pOH = 0.815.
0.153 M
[OH-] = 10^-pOH
=10^-0.815
=0.153 M
Find the pOH of a 0.25 M solution of KOH.
Find the pOH of a 1.35 x 10^-3 M solution of NaOH.
pOH = 0.60 & pOH = 2.87
pOH = -log (.25)
=0.60
If there is a 250 mL solution with a pH of -0.40, how much water is needed to increase it to pH = +0.40?
**need to dilute it
1.3 Litres
[H3O+] = 10^-(-0.40) = 2.5 M, with a volume of 250mL
[H3O+] = 10^-(+0.40) = 0.40 M, with unknown volume
C1V1 = C2V2. V2 = 1562.5 mL
So the whole flask will have a total volume of 1562.5 mL but it will be 1562.5 mL - 250 mL of HBr = 1312.5 mL of just water added.
If the [H3O+] has increased from 10^-6 to 10^-7, it has increased by a factor of ____
10^-6 to 10^-8?
10^-6 to 10^-10?
factor of 10
factor of 100
factor of 10,000
Find the concentration of [H3O+] in a solution if the pH is 8.419
3.81 x 10^-9 M
[H3O+] = 10^-pH
Find the concentration of [H3O+] in a solution if the pH = 4.876.
1.33 x 10^-5
[H3O+] = 10^-pH
= 10^-4.876
=1.33 x 10^-5
What is the pH of a 0.035 M HNO3 solution of a strong acid?
1.46
pH = -log [H30+]
- log (0.035)
1. 46
Of these four Ka values, which is the strongest acid and which is the weakest acid?
a) 4.3 x 10^-7
b) 2.2 x 10^-13
c) 7.5 x 10^-3
d) 1.7 x 10^-1
SA = d
WA = b
^Ka is a ^acidity
Find the pOH of a 0.000685 M solution of NaOH, a strong monobasic.
What is the pH of the solution?
3.164
[NaOH] = [OH-] = 0.000685
pOH = -log 0.000685
pOH = 3.164
pH = 14 - 3.164
pH = 10.836
Find the pH of 25 mL of 0.045 M solution of HCl? What is the pOH?
**strong acid
pH = - log [H+]
pH = - log 0.045
pH = 1.35
14 = pOH + pH
14 = pOH + 1.35
12.65 = pOH
Formulas to find the concentrations of H+ or OH- , if given the pH or pOH?
[H+]=10−pH
[OH−]=10−pOH
Formulas for getting the ph or pOH if given the concentrations of H+ or OH-?
pH=−log[H+]
pOH=−log[OH−]
The acid ionisation constant is expressed by _________
The base dissociation constant is expressed by ________
Ka
Kb
If NH4+ Ka value is 5.6 x 10^-10, then how would you find the Kb value?
Ka x Kb = Kw
- 6 x 10^-10 x Kb = 1.0 x 10^-14
- 8 x 10^-5
(base ionisation constant for NH3)
What is the equilibrium expression for weak bases? (because strong bases dissociate completely and there is no equilibrium to calculate..)
NH3 + H2O<−−>NH41+ + OH−
Kb = [NH4+][OH-] / [NH3]
Looking on the acid/base info table, what are the Ka values for HF and HCO3^1-?
Stronger one?
Highest conductivity?
- 5 x 10^-4
- 6 x 10^-11
HF
HF
HF + H2O−−>H3O+ + F−
What is the equilibrium expression for the ionisation of this hydrogen fluoride?
Ka = [H3O +][F-] / [HF]
Ka represents the equilibrium constant for weak or strong acids?
weak
H2S + C2H5COO− <−−> HS− + C2H5COOH
(weaker/stronger acid or base?)
1st one is the ______________
2nd one is the ____________
3rd one is the ____________
4th one is the ______________
If Keq = 10.0 , are products or reactants favoured?
WA, WB, SB, SA
PRODUCTS
C6H5OH + HS- <–> C6H50- + H2S
1st one is the ____________
2nd one is the __________
3rd one is the ___________
4th one is the ____________
Keq = 0.0019. Are products or reactants favoured?
Weaker acid
weaker base
stronger base
stronger acid
REACTANTS FAVOURED
HSO3− + HPO42− <−> H2PO4− + SO32−
(weaker/stronger acid or base?)
1st one is the ___________
2nd one is the __________
3rd one is the _________
4th one is the ____________
Are these amphiprotic?
stronger acid
stronger base
weaker acid
weak base
YES.
HC2O4− + HSO3− <−−> C2O42− + H2SO3
(weaker/stronger acid or base?)
1st one is the _______
2nd one is the ________
3rd one is the ________
4th one is the _________
SPECIAL NAME given to substances that act as a base or acid?
weaker acid
weaker base
stronger base
stronger acid
AMPHIPROTIC
For acids and bases, if Keq < 1, then ___________ are favoured
If Keq > 1, than ______ are favoured
(products or reactants?)
reactants
products
NH4+ + HCOO− <−−> NH3 + HCOOH
(weaker or stronger base/acid)
NH4+ is the ____________
HCOO- is the ______________
NH3 is the __________
HCOOH is the ________
shift to the left/right?
weaker acid
weaker base
stronger base
stronger acid
LEFT
Does equilibrium favour the side with the weaker or stronger acids? (always)
weaker
HSO4− + H2BO3 <−−> SO42− + H3BO3
Which of the two acids is stronger?
Will it shift right or left in the rxn?
HSO4-
Shift left
HCN + F− <−−> CN− + HF
Which is the strongest of the two acids?
Will rxn shift left or right?
HF (above HCN on the info table), shift left
Find the [H+] and the [OH-] in 45.00 mL of 0.00378 M of NaOH solution:
**it’s a strong base
2.65 x 10^-12 M
Let [H+] be the unknown, as we know the [OH-] concentration:
[H+] = (1.00 x 10^-14) / 0.00378
What do these ratios represent?
[H+] > [OH-]
[H+] < [OH-]
[H+] = [OH-]
acidic
basic
neutral
Find [H3O+] in 0.20 Sr(OH)2
**a strong base so there will be low concentration of hydronium
2.5 x 10^-14
Find the [OH-] in 0.25 M HClO4.
**a strong acid so hydroxide will be naturally low in concentration
4.0 x 10^-14
[H3O+][OH-] = 1.00 X 10^-14
[0.25][?] = 1.00 X 10^-14
Hydronium or Hydroxide?
ALL acids produce ___ in water.
ALL bases produce ___ in water.
H3O+, OH-
If heat is increased, then the conductivity of H30+ & OH- ______
If heat is decreased, conductivity _____
Will Kw be altered by the temperature increase?
increases, decreases, yes
Kw = [H30+] [OH-] . What does Kw equal numberically?
1.00 x 10^-14, only at 25 C
Water has it’s own Keq constant.
What is the formula?
Kw = [H+][OH-] = 1.00 x 10^-14
True or False?
A strong acid such as HCl will conduct electricity.
Strong bases such as NaOH conduct electricity
Pure H2O would conduct electricity better than tap water.
true, true, false
For an acqueous solution to be an electrical conductor, there needs to be _____ in the solution
ions
Changing from an acid into a conjugate base:
HSO3^1- –>
N2H5^1+ –>
SO3^2
N2H4
3rd rule: Where to add the H+, to make a conjugate acid from a base, to a compound that contains nitrogen?
Add the H+ to the end of the molecule. CH3NH2 (base) –> CH3NH3+
2nd rule: Where to add the H+ proton to an organic molecule such as COO- , to change from a base into an conjugate acid?
At the end of the molecule.
CH3CH2COO- (conjugate base) –> CH3CH2COOH (conjugate acid)
If a base is negative, where does the H+ get placed? C2O4^2-
At the front of the compound…HC2O4^1-
To make the conjugate acid of any base, do these two things:
…
1. add an H+ atom
2. add one positive charge (+)
The conjugate of the base HCO3^- is…
H2CO3. (with one positive charge added, the neg. disappears)
A conjugate acid/base pair is simply the difference of the _____ ion
H+
True or False?
Strong Bases dissociate and conduct electricity? ___
Weak Bases do not conduct electricity. ___
TRUE & TRUE
A strong acid breaking into ions is called ______ and always produces ______ [H3O+] ions
A strong base breaking into ions is called ________ and always produces _____ [OH-] ions
ionisation, hydronium
dissociation, hydroxide
Since a strong acid 100% completely ionises in water, which reactant and which product will have equal [] when the reaction is completed?
HCL + H20 <−−> H30+ + Cl−
[HCL] = [H3O+]
These 10 bases are examples of strong bases: (try to name as many as possible)
LiOH
KOH
FrOH
NaOH
RbOH
CsOH
Ca(OH)2
Sr(OH)2
Ba(OH)2
Ra(OH)2
These 6 are examples of strong acids:
HClO4 (perchloric acid)
HI (hydroiodic acid)
HBr ( hydrobromic acid)
HCl (hydrochloric acid)
HNO3 (nitric acid)
H2SO4 (sulphuric acid)
Acid or Base?
Diprotic substances are ____
Dibasic substances are _____
Monoprotic substances are ____
Monobasic substances are ____
acids
bases
acids
bases
If an acid or base dissolves completely in H2O, then it is a weak/strong acid/base?
If it doesn’t, it is a weak/strong acid/base?
Reactions that go to completion are ______ acids/bases.
Reactions that reach equilibrium are ____ acids/bases
weak
strong
strong
weak
Acid or bases?
Molecules with -OH are ____
Molecules with -COOH are _____
C6H5OH is a _____
acids, organic acid, acid
Acid or Base?
NaOH, KOH, Ca(OH)2, NH3
BASE
Acid or Base?
HCL, HNO3, H2SO4, CH3COOH
ACID
An amphriprotic substance is any substance that …
Can act as an acid or a base
A polyprotic acid is a general term….
…for any acid that can donate more than one proton (H2CO3, H3PO4, etc)
A monoprotic acid is a compound that donates _____ proton (H+)
A diprotic acid is a compound that donates ____ protons (H+)
A triprotic acid is a compound that donates ____ protons (H+)
1,2,3
HCN+H2O<−−>H3O++CN−HCN + H2O <–> H3O+ + CN-HCN+H2O<−−>H3O++CN−
HCN is the Bronsted _____
H2O is the Bronsted _____
acid, base
HCN gave a proton (H+)
H2O accepted a proton (H+)
HCl + H20 <−−> H30+ + Cl−
In this rxn:
HCl is the Bronsted ______
H2O is the Bronsted ______
acid, base
HCl gave a proton (H+)
H2O gained a proton (H+)
When a substance acts as a base AND an acid, it is called ______
amphiprotic
HNO3 + H2O <–>H3O+ +CN-
The HNO3 is the _________
The H2O is the ___________
(acid or base?)
acid
base
When a compound donates a proton (H+), it is a ________ and when it receives a proton (H+), it is a _____
acid, base
What is the Bronsted-Lowry Theory?
also called the proton theory of acids and bases, whereby if:
1. a compound can donate a proton (H+) to another proton is an acid
2. a compound can receive a proton (H+) from another, it is a base
