ArrheniusAcids and Bases

Question of the Day:

Which are acids? Which are bases? How can you tell?

#8.2 Aim:

What are Arrhenius acids and

bases?

AgendaQOD (5)

Lesson: Arrhenius

theory (15)

Activity:Drawing acids and

bases (15)

Summary (5)

HW#17

Arrhenius AcidsA substance whose water solution contains

H+ as the only positive ion.

HCl H+ + Cl-

ClH Cl- H++

Does that mean that all compounds that contain H are acids?

Nope! CH4 does not release H+ in water

#8.2 Aim:

What are Arrhenius acids and

bases?

AgendaQOD (5)

Lesson: Arrhenius

theory (15)

Activity:Drawing acids and

bases (15)

Summary (5)

HW#17

Nothing!

Properties of acids are properties of the hydronium ion (H3O+)

H+ + H2O H3O+

H+ OH

H+ O

H

HH +

An H+ ion and a proton are the same. (Both have one proton, no neutrons, and no electrons).

What’s the difference between an H+ ion and a proton?

Rewriting the dissociation of HCl in H2O

HCl H+ + Cl-

ClH Cl- H++

HCl + H2O H3O+ + Cl-

HCl-

H

H

+ O OH

H

H+ Cl-

+ -

#8.2 Aim:

What are Arrhenius acids and

bases?

AgendaQOD (5)

Lesson: Arrhenius

theory (15)

Activity:Drawing acids and

bases (15)

Summary (5)

HW#17

properties of bases are properties of the hydroxide ion (OH-).

Are all compounds containing OH’s bases? Nope!

CH3OH is not a base.

Arrhenius BasesA substance whose water solution contains OH- as

the only negative ion.

NaOH

Na+ OH-

+

NaOH Na+ + OH-

#8.2 Aim:

What are Arrhenius acids and

bases?

AgendaQOD (5)

Lesson: Arrhenius

theory (15)

Activity:Drawing acids and

bases (15)

Summary (5)

HW#17

-

Some bases do not look like bases until you put them in water…

NH3 + H2O NH4+ + OH-

O

HHH

H

H

N + NHH

HHO

H

+

NH3 ?

#8.3 Aim:

How do we name acids and

bases?

AgendaQOD (5)

Lesson: Acid

strength (10)

Naming acids and

bases (10)

Activity:Acid and

base strength

(15)

Summary (5)

HW#18

Acid/base strengthThe more ions released in solution, the stronger

the acid or base

H+

H+

H+

H+

H+

H+

Cl-

Cl-Cl-Cl-

H+

H+H+

Strong acids/bases create many ions

-Complete Reaction

HH

H

XX

XX-

H+

Weak acids/bases only create a small percentage of ions

-Reversible Reaction

Which is a strong acid?

#8.2 Aim:

What are Arrhenius acids and

bases?

AgendaQOD (5)

Lesson: Arrhenius

theory (15)

Activity:Drawing acids and

bases (15)

Summary (5)

HW#17

So how can you tell if a substance is an Arrhenius

acid or base?Put it in water and see what ions are released!

OR…

Look at Table of Acid and Base Strength

#8.2 Aim:

What are Arrhenius acids and

bases?

AgendaQOD (5)

Lesson: Arrhenius

theory (15)

Activity:Drawing acids and

bases (15)

Summary (5)

HW#17

Check for understanding:

According to Arrhenius theory of acids, citric acid in oranges and acetic acid in vinegar are classified as acids because their aqueous solutions contain

1. hydrogen atoms2. hydrogen ions3. hydroxide atoms4. hydroxide ions

#8.2 Aim:

What are Arrhenius acids and

bases?

AgendaQOD (5)

Lesson: Arrhenius

theory (15)

Activity:Drawing acids and

bases (15)

Summary (5)

HW#17

Check forUnderstanding:

When an Arrhenius base is dissolved in H2O, the only negative ion present in the solution is

1. OH-

2. H3O-

3. H-

4. O2-

Activity: Acids and basesEach pair will be given two substances. For each, use your reference

table along with your notes to follow each step:1. Is your substance an acid or a base?2. What kind of ions will its water solution contain? 3. Draw what will happen to your acid or base when you put it in

water.For example…

Summary

Which is an acid? Which is a base?

HNO3 + H2O H3O+ + NO3-

NH3 + H2O OH- + NH4+

acid

base

#8.2 Aim:

What are Arrhenius acids and

bases?

AgendaQOD (5)

Lesson: Arrhenius

theory (15)

Activity:Drawing acids and

bases (15)

Summary (5)

HW#17

#8.2 Aim:

What are Arrhenius acids and

bases?

AgendaQOD (5)

Lesson: Arrhenius

theory (15)

Activity:Drawing acids and

bases (15)

Summary (5)

HW#17

#8.2 Aim:

What are Arrhenius acids and

bases?

AgendaQOD (5)

Lesson: Arrhenius

theory (15)

Activity:Drawing acids and

bases (15)

Summary (5)

HW#17