Unit 4 Flashcards by Alexandra Cavanagh

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

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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

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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

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

pH + pOH = 14.00

pH = 10.51

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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

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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

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

0.153 M

[OH-] = 10^-pOH

=10^-0.815

=0.153 M

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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

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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.

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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

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

3.81 x 10^-9 M

[H3O+] = 10^-pH

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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

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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

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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

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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

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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

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

[H+]=10−pH

[OH−]=10−pOH

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

pH=−log[H+]

pOH=−log[OH−]

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The acid ionisation constant is expressed by _________

The base dissociation constant is expressed by ________

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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)

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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]

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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

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HF + H2O−−>H3O+ + F−

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

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

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Ka represents the equilibrium constant for weak or strong acids?

weak

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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