Acids and Bases: The Final Countdown

Shireen Rudina

Arrhenius Theory

In water, acids dissociate to form H+ and bases dissociate to form OH-HCl H+ + H2O

Ba(OH)2 Ba+2 + 2OH-

Neutralization reaction:

Acid + Base => Salt + WaterHA + BOH BA + H2O

Bronsted-Lowry Theory

Acids = H+ donorsBases= H+ acceptors

NH3 + H2O NH4+

so NH3 is a base

Every acid-base reaction has a conjugate acid and base

Label the acid/base, and conjugate acid/base

HNO3 + H2O H3O+ + NO3-

Acid + Carbonate Salt + H2O + CO2

Egg: CH3COOH + CaCO3 Ca(CH3COO) + H2O

+ CO2

Baking Soda & Vinegar:CH3COOH + NaHCO3

CH3COONa + H2O + CO2

Buffers

• Weak acid and its conjugate base

• Keep the pH around pKa of the acid

• Has a buffering capacity

Round 1: Multiple Choice

Questions are worth 10 points

What is true of a strong acid?

A. Has a Ka < 1

B. It can have a strong conjugate base

C. Can be neutralized by a strong base to form a salt

D. It has a pH close to 5

Which of the following is NOT a strong acid?

A. H2SO4

B. HI

C. HF

D. HNO3

E. HBr

Which of the following is NOT a strong base?

A. KOH

B. LiOH

C. Ba(OH)2

D. BOH

The conjugate acid of a weak base can be:

A. Only a strong acid

B. Only a weak acid

C. Either a strong or weak acid

A weak base:

A. Is very dilute

B. Dissociates a lot in water

C. Dissociates a little in water

D. Does not react with an acid

I want to make a buffer at pH=9. Which conjugate acid-base pair could I use?

Acid pKa Base

A CH3COOH 4.8 CH3COONa

B NH3 9.2 NH4+

C C6H5OH 9.9 C6H5OH-

D H2O 15 OH-

Round 2: Short Answer

20 points

What is the one molecule that can be an acid or a base?

EXTRA +10 for the word that describes molecules that can be acids

or bases (Italian is fine)

Write the equation for Ka

If I put .7 M of HCl in water, what is [H+]?

If I put .5 M of the strong base Ca(OH)2 in water, how many moles of OH will I have?

What is the conjugate acid of HSO4

-?

Write out an example of a neutralization reaction