Acid and Base Reactions

Shireen Rudina

ingegneria biologica

Equipe de dibattito

Arrhenius Theory

• In water, acids dissociate to form H+ and bases dissociate to form OH-

HCl + H2O H3O++ Cl-

Concept Q: Which of these options are only acids?

1. HCl, NH3, HI

2. H2CO3, NaOH, HBr

3. H2CO3, NH4+, HCl

4. HI, KOH, HBr

Arrhenius Strong/Weak Acids

• Strong acid– Dissociates completely

• Weak acids- everything else

CH3COOH (aceto)

NH4+

HClHNO3

H2SO4

HBrHIHClO4

Arrhenius Strong/Weak Bases

• Strong bases:LiOHNaOHKOHRbOHCsOHBa(OH)2

Ca(OH)2

Sr(OH)2

• Weak bases: everything else

In teams: Calculate the pH of a 0.05 M HBr solution

1. Is HBr a strong acid? How much does it dissociate?

2. What is [H+]?

In teams: A 0.128 M solution of uric acid (HC5H3N4O3) has a pH of 2.39. Calculate the Ka of uric acid.

1. What is the equation for Ka?

2. What variables do we have?

• http://www.youtube.com/watch?v=YqEK5ECcsDo

• http://www.youtube.com/watch?v=vyOnGA0cmp0

• http://www.elmhurst.edu/~chm/vchembook/183neutral.html

In teams: You have an unknown acid. When you put 1 M in water, you see a pH that corresponds to a specific dissociation

percentage.

• Find the Ka for the acid that dissociates:– Team 1: 1%– Team 2: 2%– Team 3: 0.1%

• What acid do you have?

Arrhenius Acid/Base Reaction

Acid + Base = Salt + WaterHBr + NaOH NaBr + H2O

Neutralization

Phenolphthalein:Purple if pH > 7Colorless if pH<7

A Neutralization Experiment

CO2 + H2O --> H2CO3

Ca(OH)2 + H2CO3 --> CaCO3 + 2 HOH

What is the result of a neutralization reaction: NaOH + H2CO3?

1. NaH2 + H2O

2. NaH2 + H2O + CO3

3. NaHCO3 + H2O

4. NaCO3 + H2O

Bronsted-Lowry Acid/Base Reaction

Conjugate acids and bases