Acid and Base Strength Acids Have a sour taste.
-
Upload
brook-francis -
Category
Documents
-
view
222 -
download
1
Transcript of Acid and Base Strength Acids Have a sour taste.
Acid and Base StrengthAcid and Base Strength
AcidsHave a sour taste.
AcidsTurn blue litmus red.Turn methyl orange red.
AcidsWill react with:some metals to produce a salt and H2.
metal oxides to produce a salt and H2O.
metal carbonates to produce a salt, H2O, and CO2.
bases to produce a salt and H2O.
Mg + 2HCl MgCl2 + H2
MgO + 2HCl MgCl2 + H2O
MgCO3 + 2HCl MgCl2 + H2O + CO2
Mg(OH)2 + 2HCl MgCl2 + 2H2O
AcidsAre electrolytes.
Conduct an electric current when dissolved.
BasesHave a bitter taste.
Coffee itself is acidic, but it contains an alkaline compound – caffeine – which contributes to its bitter taste.
BasesFeel slimy or slippery to the touch.
BasesTurn red litmus blue.Turn methyl orange yellow.Turn phenolphthalein pink.
Litmus pH scale.
BasesReact with acids to produce salt and H2O.
HCl + NaOH NaCl + H2O
BasesAre electrolytes.
ReviewReview
Properties of Acids◦Taste sour.◦Turn litmus red.◦Proton (H+) donors.◦ Inc. [H3O+] in aqueous
solutions.
Properties of Bases◦Taste bitter.◦Turn litmus blue.◦Proton acceptors.◦ Inc. [OH-] in aqueous
solutions.
ReviewReview
pH Scale◦Traditionally 0 - 14.
Can have pH < 0 or > 14.◦pH < 7 Acidic solution.◦pH = 7 Neutral solution.◦pH > 7 Basic solution.
pH ScalepH Scale
Acidic Basic
0 1 2 3 4 5 6 7 8 9 10
11
12
13
14
pH Scale
HCl, A Strong AcidHCl, A Strong Acid
HF, A Weak AcidHF, A Weak Acid
As [H+] Increases, [OH-1] Decreases
1x10-13 M
1x10-12 M
1x10-11 M
1x10-10 M
1x10-9 M
1x10-8 M
1x10-7 M
1x10-6 M
1x10-5 M
1x10-4 M
1x10-3 M
1x10-2 M
1x10-1 M
1x10-13 M
1x10-12 M
1x10-11 M
1x10-10 M
1x10-9 M
1x10-8 M
1x10-7 M
1x10-6 M
1x10-5 M
1x10-4 M
1x10-3 M
1x10-2 M
1x10-1 M
[H+]
[OH
-1]
Neutral Solution
Acid added to neutral solutionBase added to neutral solution
In any aqueous solution:◦ [H+] [OH-1] = 1x10-14
◦ As [H+] goes up, [OH-1] must decrease.◦ As [OH-1] goes up, [H+] must decrease.
In other words, adding an acid to water causes the solution to become more acidic and less basic.
Adding a base to water causes the solution to become less acidic and more basic.
If [H+] = 1x10-3 M, what is [OH-1]?◦ [H+][OH-1] = 1x10-14
◦ (1x10-3 M)[OH-1] = 1x10-14
◦ [OH-1] = (1x10-14) / (1x10-3)◦ [OH-1] = 1x10-11 M
If [OH-1] = 1x10-8 M, what is [H+]?◦ [H+][OH-1] = 1x10-14
◦ [H+](1x10-8 M) = 1x10-14
◦ [H+] = (1x10-14) / (1x10-8 M)◦ [H+] = 1x10-6 M
pH = power of Hydrogen◦ negative logarithmic (powers of ten) scale.
pH = -log10[H+]◦ If [H+] = 1x10-1 M,
pH = -log(1x10-1 M) = 1◦ If [H+] = 1x10-2 M,
pH = -log(1x10-2 M) = 2◦ If [H+] = 1x10-3 M,
pH = -log(1x10-3 M) = 3
The logarithm of a number is the power to which you would have to raise a base to equal that number.◦ Unless otherwise indicated, assume the base is 10.
log(100) = 2◦ because 102 = 100
log(1000) = 3◦ because 103 = 1000
log(0.001) = -3◦ because 10-3 = 0.001
log(0.000 001) = -6◦ because 10-6 = 0.000 001
Concentrations of Hydronium and Hydroxide Ions
1.00E-14
1.00E-12
1.00E-10
1.00E-08
1.00E-06
1.00E-04
1.00E-02
1.00E+00
1 2 3 4 5 6 7 8 9 10 11 12 13
pH
Mo
lar [H3O+1]
[OH-1]
Calculations Involving pH, pOH, [H+], and [OH-] of strong Acids and Bases
pH = -log [H+]
pOH = -log [OH-]
pOH + pH = 14
What are the pH values of the following solutions?◦ 1x10-1 M H+
pH = -log(1x10-1 M) = 1◦ 1x10-3 M H+
pH = -log(1x10-3 M) = 3◦ 1x10-5 M H+
pH = -log(1x10-5 M) = 5◦ 1x10-1 M OH-1
[H+] = (1x10-14) / (1x10-1 M) = 1x10-13 M pH = -log(1x10-13 M) = 13