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Chemistry 12 > Unit 4 > Flashcards

Unit 4 Flashcards

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1
Q

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

A

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

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2
Q

Find the concentration [HCl] if the pOH = 11.819

**strong acid so, [HCl] = [H3O+]

A

1. pOH + pH = 14.00. = 2.181

2. [H3O+] = 10^-pH. = 0.00659

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3
Q

Find the pH of a 0.025 M KOH solution.

A

pH = 12.39

1. pOH = -log [OH-]. = 1.602

2. pH + pOH = 14.00. =12.39

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4
Q

Easy: Find the pOH of a solution if the pH = 3.49

A

pH + pOH = 14.00

pH = 10.51

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5
Q

What is the Kw used for?

What is the pKw?

A

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

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6
Q

Find the [Sr(OH)2] of a solution if the pOH = 1.319

A

[OH-] = 10^-1.319

=0.0480 M

Since Sr(OH)2 –> Sr2+ + 2OH-

the [Sr(OH)2] = 0.0240 M

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7
Q

Find the [NaOH] of a solution if the pOH = 0.815.

A

0.153 M

[OH-] = 10^-pOH

=10^-0.815

=0.153 M

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8
Q

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.

A

pOH = 0.60 & pOH = 2.87

pOH = -log (.25)

=0.60

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9
Q

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

A

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.

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10
Q

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?

A

factor of 10

factor of 100

factor of 10,000

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11
Q

Find the concentration of [H3O+] in a solution if the pH is 8.419

A

3.81 x 10^-9 M

[H3O+] = 10^-pH

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12
Q

Find the concentration of [H3O+] in a solution if the pH = 4.876.

A

1.33 x 10^-5

[H3O+] = 10^-pH

= 10^-4.876

=1.33 x 10^-5

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13
Q

What is the pH of a 0.035 M HNO3 solution of a strong acid?

A

1.46

pH = -log [H30+]

  • log (0.035)
    1. 46
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14
Q

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

A

SA = d

WA = b

^Ka is a ^acidity

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15
Q

Find the pOH of a 0.000685 M solution of NaOH, a strong monobasic.

What is the pH of the solution?

A

3.164

[NaOH] = [OH-] = 0.000685

pOH = -log 0.000685

pOH = 3.164

pH = 14 - 3.164

pH = 10.836

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16
Q

Find the pH of 25 mL of 0.045 M solution of HCl? What is the pOH?

**strong acid

A

pH = - log [H+]

pH = - log 0.045

pH = 1.35

14 = pOH + pH

14 = pOH + 1.35

12.65 = pOH

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17
Q

Formulas to find the concentrations of H+ or OH- , if given the pH or pOH?

A

[H+]=10−pH

[OH−]=10−pOH

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18
Q

Formulas for getting the ph or pOH if given the concentrations of H+ or OH-?

A

pH=−log[H+]

pOH=−log[OH−]

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19
Q

The acid ionisation constant is expressed by _________

The base dissociation constant is expressed by ________

A

Ka

Kb

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20
Q

If NH4+ Ka value is 5.6 x 10^-10, then how would you find the Kb value?

A

Ka x Kb = Kw

  1. 6 x 10^-10 x Kb = 1.0 x 10^-14
  2. 8 x 10^-5

(base ionisation constant for NH3)

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21
Q

What is the equilibrium expression for weak bases? (because strong bases dissociate completely and there is no equilibrium to calculate..)

NH3 + H2O<−−>NH41+ + OH−

A

Kb = [NH4+][OH-] / [NH3]

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22
Q

Looking on the acid/base info table, what are the Ka values for HF and HCO3^1-?

Stronger one?

Highest conductivity?

A
  1. 5 x 10^-4
  2. 6 x 10^-11

HF

HF

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23
Q

HF + H2O−−>H3O+ + F−

What is the equilibrium expression for the ionisation of this hydrogen fluoride?

A

Ka = [H3O +][F-] / [HF]

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24
Q

Ka represents the equilibrium constant for weak or strong acids?

A

weak

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25
Q

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?

A

WA, WB, SB, SA

PRODUCTS

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26
Q

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?

A

Weaker acid

weaker base

stronger base

stronger acid

REACTANTS FAVOURED

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27
Q

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?

A

stronger acid

stronger base

weaker acid

weak base

YES.

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28
Q

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?

A

weaker acid

weaker base

stronger base

stronger acid

AMPHIPROTIC

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29
Q

For acids and bases, if Keq < 1, then ___________ are favoured

If Keq > 1, than ______ are favoured

(products or reactants?)

A

reactants

products

30
Q

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?

A

weaker acid

weaker base

stronger base

stronger acid

LEFT

31
Q

Does equilibrium favour the side with the weaker or stronger acids? (always)

A

weaker

32
Q

HSO4− + H2BO3 <−−> SO42− + H3BO3

Which of the two acids is stronger?

Will it shift right or left in the rxn?

A

HSO4-

Shift left

33
Q

HCN + F− <−−> CN− + HF

Which is the strongest of the two acids?

Will rxn shift left or right?

A

HF (above HCN on the info table), shift left

34
Q

Find the [H+] and the [OH-] in 45.00 mL of 0.00378 M of NaOH solution:

**it’s a strong base

A

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

35
Q

What do these ratios represent?

[H+] > [OH-]

[H+] < [OH-]

[H+] = [OH-]

A

acidic

basic

neutral

36
Q

Find [H3O+] in 0.20 Sr(OH)2

**a strong base so there will be low concentration of hydronium

A

2.5 x 10^-14

37
Q

Find the [OH-] in 0.25 M HClO4.

**a strong acid so hydroxide will be naturally low in concentration

A

4.0 x 10^-14

[H3O+][OH-] = 1.00 X 10^-14

[0.25][?] = 1.00 X 10^-14

38
Q

Hydronium or Hydroxide?

ALL acids produce ___ in water.

ALL bases produce ___ in water.

A

H3O+, OH-

39
Q

If heat is increased, then the conductivity of H30+ & OH- ______

If heat is decreased, conductivity _____

Will Kw be altered by the temperature increase?

A

increases, decreases, yes

40
Q

Kw = [H30+] [OH-] . What does Kw equal numberically?

A

1.00 x 10^-14, only at 25 C

41
Q

Water has it’s own Keq constant.

What is the formula?

A

Kw = [H+][OH-] = 1.00 x 10^-14

42
Q

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.

A

true, true, false

43
Q

For an acqueous solution to be an electrical conductor, there needs to be _____ in the solution

A

ions

44
Q

Changing from an acid into a conjugate base:

HSO3^1- –>

N2H5^1+ –>

A

SO3^2

N2H4

45
Q

3rd rule: Where to add the H+, to make a conjugate acid from a base, to a compound that contains nitrogen?

A

Add the H+ to the end of the molecule. CH3NH2 (base) –> CH3NH3+

46
Q

2nd rule: Where to add the H+ proton to an organic molecule such as COO- , to change from a base into an conjugate acid?

A

At the end of the molecule.

CH3CH2COO- (conjugate base) –> CH3CH2COOH (conjugate acid)

47
Q

If a base is negative, where does the H+ get placed? C2O4^2-

A

At the front of the compound…HC2O4^1-

48
Q

To make the conjugate acid of any base, do these two things:

…

A

1. add an H+ atom

2. add one positive charge (+)

49
Q

The conjugate of the base HCO3^- is…

A

H2CO3. (with one positive charge added, the neg. disappears)

50
Q

A conjugate acid/base pair is simply the difference of the _____ ion

A

H+

51
Q

True or False?

Strong Bases dissociate and conduct electricity? ___

Weak Bases do not conduct electricity. ___

A

TRUE & TRUE

52
Q

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

A

ionisation, hydronium

dissociation, hydroxide

53
Q

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−

A

[HCL] = [H3O+]

54
Q

These 10 bases are examples of strong bases: (try to name as many as possible)

A

LiOH

KOH

FrOH

NaOH

RbOH

CsOH

Ca(OH)2

Sr(OH)2

Ba(OH)2

Ra(OH)2

55
Q

These 6 are examples of strong acids:

A

HClO4 (perchloric acid)

HI (hydroiodic acid)

HBr ( hydrobromic acid)

HCl (hydrochloric acid)

HNO3 (nitric acid)

H2SO4 (sulphuric acid)

56
Q

Acid or Base?

Diprotic substances are ____

Dibasic substances are _____

Monoprotic substances are ____

Monobasic substances are ____

A

acids

bases

acids

bases

57
Q

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

A

weak

strong

strong

weak

58
Q

Acid or bases?

Molecules with -OH are ____

Molecules with -COOH are _____

C6H5OH is a _____

A

acids, organic acid, acid

59
Q

Acid or Base?

NaOH, KOH, Ca(OH)2, NH3

A

BASE

60
Q

Acid or Base?

HCL, HNO3, H2SO4, CH3COOH

A

ACID

61
Q

An amphriprotic substance is any substance that …

A

Can act as an acid or a base

62
Q

A polyprotic acid is a general term….

A

…for any acid that can donate more than one proton (H2CO3, H3PO4, etc)

63
Q

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+)

A

1,2,3

64
Q

HCN+H2O<−−>H3O++CN−HCN + H2O <–> H3O+ + CN-HCN+H2O<−−>H3O++CN−

HCN is the Bronsted _____

H2O is the Bronsted _____

A

acid, base

HCN gave a proton (H+)

H2O accepted a proton (H+)

65
Q

HCl + H20 <−−> H30+ + Cl−

In this rxn:

HCl is the Bronsted ______

H2O is the Bronsted ______

A

acid, base​

HCl gave a proton (H+)

H2O gained a proton (H+)

66
Q

When a substance acts as a base AND an acid, it is called ______

A

amphiprotic

67
Q

HNO3 + H2O <–>H3O+ +CN-

The HNO3 is the _________

The H2O is the ___________

(acid or base?)

A

acid

base

68
Q

When a compound donates a proton (H+), it is a ________ and when it receives a proton (H+), it is a _____

A

acid, base

69
Q

What is the Bronsted-Lowry Theory?

A

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

70
Q
A

Chemistry 12 (4 decks)

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