ch 16 Flashcards
Arrhenius
Scientist who postulated that acids produce H+ions in aqueous solution, whereas bases produce OH–ions
Brønsted–Lowry model
States that acids are proton (H+) donors, bases are proton acceptors
HCl (acid) + H2O (base) → Cl–+ H3O+
Conjugate base
everything that remains of the acid molecule after a proton is lost
Conjugate acid
formed when a proton is transferred to the base
Conjugate acid–base pair
Consists of two substances related to each other by the donating and accepting of a single proton
acids in water
Water acts as a base accepting a proton from the acid
- Forms hydronium ion (H3O+)
Which of the following pairs represents a conjugate acid–base pair? a) HCl, HNO3 b )H3O+, OH– c) H2SO4, SO42– d) HCN, CN–
d) HCN, CN–
strong acid
- Completely ionized or completely dissociated HA(aq) + H2O(l) → H3O+(aq) + A–(aq)
- breaks apart 100%
- forward rxn predominates
weak acid
- Most of the acid molecules remain intact HA(aq) + H2O(l) ← H3O+(aq) + A–(aq)
- A- is a much stronger base than H2O
- strength of the conjugate base compared with that of water
Strong acids contain relatively __ conjugate bases
weak
what makes up a base?
type 1 and 2 metals + OH-
common strong acids
- Sulfuric acid, H2SO4
- Hydrochloric acid, HCl
- Nitric acid, HNO3
- Perchloric acid, HClO4
Oxyacids
Acidic proton is attached to an oxygen atom
Organic acids
- Have a carbon atom backbone and commonly contain the carboxyl group
- typically weak acids
weak acids have a __ base
strong
Consider a 1.0 M solution of HCl • Order the following from strongest to weakest base and explain your answer – H2O(l) – A–(aq) (from weak acid HA) – Cl–(aq)
A-, H2O, Cl-
water is _
amphoteric
- can be both an acid (H3O+) and a base (OH-)
at 25ºC, Kw =
Kw = [H+] [OH-] = 1.0 x 10^-14
*no matter what the solution contains
[H+] = [OH–]
neutral solution
[H+] > [OH–]
acidic solution
[H+] < [OH–]
basic solution
in an acidic, basic, or neutral solution Kw always equals
Kw = [H+][OH–] = 1.0 × 10^-14
In the context of an acidic aqueous solution, which of the following statements is correct?
a) [H+] < 1.0 × 10^-7 M
b) [H+] > 1.0 x 10^-7 M
c) [OH–] > 1.0 × 10^-7 M
d) [H+] < [OH-]
b
an acid/base reaction is also called a
neutralization reaction
pH =
− log [H+]
pH scale
Provides a convenient way to represent solution acidity
as [H+] increases, pH __
decreases
sig figs
The number of decimal places in the log is equal to the number of significant figures in the original number
pH range
7 is neutral
> 7 is basic
< 7 is acidic
*The lower the pH, the more acidic the solution
pH scale
scale is from 0-14
- acidic: 0-6.9
- neutral: 7
- basic: 7.1-14
pOH =
- log [OH-]
[H+] =
10^-pH
[OH-] =
10^-pOH
pH + pOH =
14
[H+] [OH-] =
1.0 x 10^ -14
calculate the pH for 1.0×10^-4 M H+
4.00
pH = –log[H+] = –log(1.0 × 10–4 M) = 4.00
calculate the pH for 0.040 M OH–
12.60
The pH of a solution is 5.85. What is the [H+] for this solution?
[H+] = 1.4 × 10^-6 M
calculate the pOH for 1.0×10^-4 M H+
10.00
calculate the pOH for 0.040 M OH–
1.40
The pH of a solution is 5.85. What is the [OH–] for this solution?
7.1 × 10^-9 M
Consider an aqueous solution of 2.0 ×10–3 M HCl. What is its pH?
2.70
Calculate the pH of a 1.5 ×10–11 M solution of HCl
7.00
Calculate the pH of a 1.5 ×10–2 M solution of HNO3
1.82
