What are we going to discuss? Tables K and L in the Reference Tables list a few of the most common...

What are we going to discuss? Tables K and L in the Reference Tables list a few

of the most common Acids and Bases, but what are Acids and Bases.

Acids and Bases have easy to identify properties.

In this unit will learn about these properties, and the important reactions that occur between acids and bases.

Properties of Acids They are electrolytes, that break up into ions in water, that

conduct electricity in aqueous solutions○ Strong acid: good conductor○ Weak acid: poor conductor

Sour Taste

React with most metals to produce H2 (g)

React with bases to form H2O and salt

React with indicators to change colorturn litmus redphenolphthalein turns colorlesspH values are 0.0-6.9see Table M for others

Properties of Bases Electrolytes conduct electricity in aqueous solutions

○ Strong base: good conductor

Bitter Taste

Feel slippery (like soap)

React with acids to form H2O and salt

React with indicators to change colorlitmus turns bluephenolphthalein turns pink pH values are 7.1-14

Arrhenius’ Theory on Acids and Bases

Arrhenius Acid Definition: a substance that ionizes in water to

give hydrogen ions (proton) or a Hydronium ion: H+ or H3O+

Ex: Hydrochloric acid, HCl (a strong acid). HCl (g) H+ (aq) + Cl- (aq)

ACIDIC solutions are formed when an acid transfers a proton to water.

Hydronium Ion

The H+ interacts strongly with a lone pair of electrons on the oxygen of a water molecule. The resulting ion, H3O

+ is

called the hydronium ion.

Ex: HCl + H2O H3O+1 + Cl-1

Arrhenius’ Bases Definition: a substance that ionizes in water to

give hydroxide ions: OH-

Example: NaOH, NH3

NaOH (s) Na+(aq) + OH- (aq)

NH3 + H2O NH4+1 + OH-

SALTS A salt is an ionic compound that does not produce

an H+ ion or OH- ion when dissolved in water.

Salts are not acids or bases they are neutral substances.

Ex. ○ NaCl○ MgCl2

Binary acids –two elements - H+ *

Hydrogen _____ ide Hydrogen chloride Hydrogen fluoride Hydrogen sulfide Hydrogen bromide

Hydro_____ic acid Hydrochloric acid Hydrofluoric acid Hydrosulfuric acid Hydrobromic acid

hydrogen _____ ide becomes hydro_____ic acid

Ternary acids3 elements: H+ and a polyatomic ion

Hydrogen _____ate Hydrogen sulfate Hydrogen chlorate Hydrogen nitrate Hydrogen phosphate

_________ic acid Sulfuric acid chloric acid nitric acid Phosphoric acid

Hydrogen _____ate becomes _________ic acid

Hydrogen ________ite_________ ous acid

Hydrogen _____ite Hydrogen nitrite Hydrogen sulfite Hydrogen chlorite

_______ous acid Nitrous acid Sulfurous acid Chlorous acid

Hydrogen _____ite becomes _______ous acid

Table K and Table L These two tables list the most common acids

and bases.

The top 4 acids on table K are all strong acids while the last 2 are weak acids.

The top 3 bases on table L are strong bases while that last 1 is a weak base.

Strengths of Acids

Strong acids: ionize completely which means if 100 molecules dissolve in water all 100 will break up into ions

Examples:

HCl H+ + Cl-

H2SO4 2H+ + SO4-2

Strengths of Acids Weak acids: ionize slightly or only a

small percentage will break up into ions

Example: acetic acid (vinegar)

CH3COOH CH3COO- + H+

****note if an organic compound ends in COOH it’s a weak acid!!!

Strengths of Bases

Strong bases: ionize completely

Example:

NaOH Na+ +OH-

Strengths of Bases

Weak base: ionizes slightly

Example: ammonia

NH3 + H2O NH4+ + OH-

Acid and Base Reactions

You will need to be familiar with 2 reactions that involve acids and bases.

The first reaction only involves an acid with a metal.

The second reaction deals with reacting an acid with a base to produce a salt and water or neutralization.

Neutralization Reaction

In a neutralization reaction an Acid will react with a base to produce salt and water.

Three ways we can express neutralization reactions:1. Word equation

2. Formula equation

3. Net ionic equation

A net ionic equation has only the ions that have taken part in the reaction. In the reaction the ions that do not change are omitted, these ions are called spectator ions. See example

Neutralization

HCl + NaOH

acid + base water + a salt

HOH + NaCl

Hydrochloric Acid + Sodium Hydroxide yields Water + Sodium Chloride

H+(aq) + Cl-(aq) + Na+

(aq) + OH-(aq) H2O + Na+

(aq) + Cl-(aq)

H+(aq) + OH-

(aq) H2O

This is the net ionic equation for all neutralization reactions this equation shows how the ions are neutralized.

Try This One

H2SO4 + 2NaOH 2H2O + Na2SO4

2H+ + SO4-2 + 2Na+ + 2OH- 2H2O + 2Na+ + SO4

-2

H+ + OH- H2O

Sulfuric acid + sodium hydroxide yields water + sodium sulfate

Concentration of H+ in Acids A. 1.0 M HCl (monoprotic acid)

HCl H+ + Cl-

Produces 1 H+ so the concentration of H+ is 1.0 M

[H+] = 1.0 M

Concentration of H+ in Acids B. 1.0 M H2SO4 (diprotic acid)

H2SO4 2H+ + SO4-2

Produces 2 H+ so the concentration of H+ is 2(1.0 M)

[H+] = 2.0 M

Concentration of OH- in Bases A. 1.0 M KOH

KOH K+ + OH-

Produces 1 OH- so the concentration of OH- is 1.0 M.

[OH-] = 1.0 M

Concentration of OH- in Bases B. 1.0 M NaOH

NaOH Na+ + OH-

Produces 1 OH- so the concentration of OH- is 1.0 M.

[OH-] = 1.0 M

Concentration of OH- in Bases C. 1.0 M Ca(OH)2

Ca(OH)2 Ca+2 + 2OH-

Produces 2 OH- so the concentration of OH- is 2(1.0 M).

[OH-] = 2.0 M

Concentration of OH- in Bases D. 1.0 M Mg(OH)2

Mg(OH)2 Mg+2 + 2OH-

Produces 2 OH- so the concentration of OH- is 2(1.0 M).

[OH-] = 2.0 M

Titration An Acid-Base titration is a lab technique used find

the concentration of an acid or a base by neutralizing it.

During a titration you add volumes of a base to an acid until it is neutralized.

Using the Acid-Base titration formula listed on Table T you can solve for your unknown concentration.

Acid- Base Titrations

MaVa = MbVb (Table T)

Ma = molarity of H+

Va = volume of acid

Mb = molarity of OH-

Vb = volume of base

Titration-Setup

Titrations (Neutralization) Problems Ex. What volume of 0.50M HCl is required to neutralize

100mL of 2.0M NaOH?

MaVa = MbVb

Ma = .5M

Va = ??

Mb = 2.0M

Vb = 100mLPlug in and solve

0.5(x) = 2.0(100)X = 400mL HCl

Try the rest on your own!!!

pH Scale A scale, called the pH scale, has been

developed to express [H+] as a number from 0 to 14.

A pH of 0 is strongly acidic

A pH of 7 is neutral

A pH of 14 is strongly basic

pH Scale

Acid – Base Indicators An indicator is something that changes its color

when it gains or loses a proton or an H+ ion.

There are several different indicators and they change differently when exposed to different pH values.

On your reference tables there is a list of common

indicators that show the color changes at varying pH values.

See Table M You can use multiple indicators to find the

approximate pH of a substance