Acids and Bases
Acids
Produces H+ ions in water (H3O+) Sour taste Corrode metals Contain electrolytes React to form salt and water with bases pH is less than 7 Turns blue litmus paper red (Blue to Red A-CID) |
Bases
Produce OH- ions in water Chalky, bitter taste Are electrolytes Feel soapy, slippery React to form salt and water with acids pH is greater than 7 Turns red litmus paper to blue (Basic Blue) |
Those are the properties of acids and bases, but what are acids and bases? There are two definitions, the Arrhenius definition, and the Bronsted-Lowery definition.
Arrhenius Definition
(Traditional) Acid- Produces H+ ions, or Hydronium ions (H3O+) Base- Produces OH- ions Problem- some bases don't have hydroxide ions |
Bronsted-Lowery Definition
Acid- Donates protons out Base- Accepts protons in A proton is really just a Hydrogen atom that has lost it's electron! |
Common Acids
HCl- Hydrochloric Acid HNO3- Nitric Acid HC2H3O2- Acetic Acid H2SO4- Sulfuric Acid H3C6H5O7- Citric Acid H2CO3- Carbonic Acid H3PO4- Phosphoric Acid H2C2O4- Oxalic Acid |
Common Bases
NaOh- Sodium Hydroxide KOH- Potassium Hydroxide Ba(OH)2- Barium Hydroxide Mg(OH)2- Magnesium Hydroxide Al(OH)2- Aluminum Hydroxide |
Naming Acids
If the anion ends with "-ide" it will change to Hydro_______ic Acid, with the root name of the anion going in the blank.
Ex. Sulfide
Hydrosulfuric Acid
If the anion ends with "-ate" it will change to _______ic Acid.
Ex. Sulfate
Sulfuric Acid
If the anion ends with "-ite" it will change to _______ous Acid.
Ex. Sulfite
Sulfurous Acid
If the anion ends with "-ide" it will change to Hydro_______ic Acid, with the root name of the anion going in the blank.
Ex. Sulfide
Hydrosulfuric Acid
If the anion ends with "-ate" it will change to _______ic Acid.
Ex. Sulfate
Sulfuric Acid
If the anion ends with "-ite" it will change to _______ous Acid.
Ex. Sulfite
Sulfurous Acid
Hydrates and Salts
We all know what salt is, but what about hydrates? Hydrates are ionic compounds that have a certain number of water molecules 'attached' to the crystalline structure of the compound. Without the water molecules, the ionic compound is called an anhydrous salt; with water it is called the hydrate, or hydrated form of the compound.
Formula
The formula for writing a hydrate is A ● n H2O, where A is the Anhydrous Salt, n is the number of water molecules loosely bonded to the ionic compound, and H2O is obviously the water molecules.
You write these formulas by first writing the correct formula for the anhydrous compound, followed by that big dot. Then use the Greek prefix in the name to tell how many water molecules are attached.
Ex. Aluminum Chloride Dihydrate
AlCl3 ● 2H2O
Ex. CaCl2 ● 2H2O
Calcium Chloride Dihydrate
We all know what salt is, but what about hydrates? Hydrates are ionic compounds that have a certain number of water molecules 'attached' to the crystalline structure of the compound. Without the water molecules, the ionic compound is called an anhydrous salt; with water it is called the hydrate, or hydrated form of the compound.
Formula
The formula for writing a hydrate is A ● n H2O, where A is the Anhydrous Salt, n is the number of water molecules loosely bonded to the ionic compound, and H2O is obviously the water molecules.
You write these formulas by first writing the correct formula for the anhydrous compound, followed by that big dot. Then use the Greek prefix in the name to tell how many water molecules are attached.
Ex. Aluminum Chloride Dihydrate
AlCl3 ● 2H2O
Ex. CaCl2 ● 2H2O
Calcium Chloride Dihydrate
What is the pH Scale?
The pH scale ranges from 0-14 and indicates how strong an acid or base is.
0-7 Acidic
7 Neutral
7-14 Basic
Solving for pH
pH = -log [H3O+]
Ex. What is the pH of a 1.0x10^-3M HCl solution?
[H3O+] = 1.0x10^-3
pH = -log(1.0x10^-3)
Plug in to Graphing Calculator to solve!
pH = 3
Solving Backwards! (For the same problem)
[H3O+] = 10^-pH
[H3O+] = 10^-3
Ex. The pH of a solution is measured to be 7.52. What is the [H3O+]? What is the [OH-]? Is this solution an acid or base?
[H3O+]
[H+] = 10^-7.52
[H+] = 3.02x10^-8
pOH
14 = 7.52 + pOH
6.48 = pOH
[OH-]
[OH-] = 10^-6.48
[OH-] = 3.31x^-7
0-7 Acidic
7 Neutral
7-14 Basic
Solving for pH
pH = -log [H3O+]
Ex. What is the pH of a 1.0x10^-3M HCl solution?
[H3O+] = 1.0x10^-3
pH = -log(1.0x10^-3)
Plug in to Graphing Calculator to solve!
pH = 3
Solving Backwards! (For the same problem)
[H3O+] = 10^-pH
[H3O+] = 10^-3
Ex. The pH of a solution is measured to be 7.52. What is the [H3O+]? What is the [OH-]? Is this solution an acid or base?
[H3O+]
[H+] = 10^-7.52
[H+] = 3.02x10^-8
pOH
14 = 7.52 + pOH
6.48 = pOH
[OH-]
[OH-] = 10^-6.48
[OH-] = 3.31x^-7
Titration
Titration is you add an acid to a base, or a base to an acid until they are equal.
( [H3O+] = [OH-] )
The pH has to be equal to 7, and you also must take into consideration how much of H+ and OH- is being released to get normality, which can be labeled as the true molarity.
Ma (#H) Va = Mb (#H) Vb
Acids Bases
Ex. In a titration 27.4 mL of 0.0154 M Ba(OH)2 is added to 20.0 mL sample of HCl of an unknown concentration. What is the molarity of the HCl solution?
First determine the normality.
2 moles HCl to neutralize 1 mole Ba(OH)2
Then use the formula
Ma (1) (20) = 0.154 (2) (27.4)
Ma (20) = .84392
20 20
Ma= [0.0422]
Titration is you add an acid to a base, or a base to an acid until they are equal.
( [H3O+] = [OH-] )
The pH has to be equal to 7, and you also must take into consideration how much of H+ and OH- is being released to get normality, which can be labeled as the true molarity.
Ma (#H) Va = Mb (#H) Vb
Acids Bases
Ex. In a titration 27.4 mL of 0.0154 M Ba(OH)2 is added to 20.0 mL sample of HCl of an unknown concentration. What is the molarity of the HCl solution?
First determine the normality.
2 moles HCl to neutralize 1 mole Ba(OH)2
Then use the formula
Ma (1) (20) = 0.154 (2) (27.4)
Ma (20) = .84392
20 20
Ma= [0.0422]