Notes on Acids and Bases

Notes on Acids and Bases

Properties of Acids:Properties of Acids:

Taste sour Conduct electricity (aqueous acids) Contains H+, (the more H+, the stronger

the acid) Very reactive Cause indicators to change colors

Uses of Acids:Uses of Acids:

Metal cleaners Batteries Digest food- found in our stomachs Foods Paints Plastics

Examples of Acids:Examples of Acids:

Hydrochloric acid (HCl)- in stomach

Citric acid (in citrus fruits like lemons)

Acetic acid (vinegar)

Arrhenius AcidsArrhenius Acids

Hydrogen containing compound that ionize hydrogen ions (H+) in aqueous solutions

Monoprotic- acids that contain 1 ionizable hydrogen (nitric acid)

Diprotic- 2 ionizable hydrogens (sulfuric acid) Triprotic- 3 ionizable hydrogens (phosphoric

acid)

Properties of Bases:Properties of Bases: Taste bitter (very hazardous) Contains OH- (the more OH-, the stronger the

base) Typically a solid Cause indicators to change colors Slippery when wet None of the foods we eat are bases, few

exceptions (tums, milk of magnesia)

Uses of Bases:Uses of Bases:

Cleansers Drain cleaners Soap Shampoo Laundry detergent

Examples of Bases:Examples of Bases:

Sodium hydroxide (NaOH)

Ammonia

Lime water Ca(OH)2

Arrhenius BasesArrhenius Bases

Hydroxide containing compound that ionize hydroxide ions (OH-) in aqueous solutions

Amphoteric- can act as an acid or a base

Bronsted-Lowery AcidsBronsted-Lowery Acids

Acid is a hydrogen ion (H+) donor Conjugate base is the particle that remains

when the acid donates a hydrogen ion

HCl Cl-

(acid) (conjugate base)

Bronsted-Lowery BasesBronsted-Lowery Bases

Base is a hydrogen ion (H+) acceptor Conjugate acid is the particle that remains

when the acid gains a hydrogen ion

NH3 NH4

(Base) (conjugate acid)

Brosted-Lowery Acids/BasesBrosted-Lowery Acids/Bases

NH3 + H2O NH4+ + OH-

HCl + H2O H3O+ + Cl-

H2SO4 + H2O HSO4- + H3O+

pH ScalepH Scale Ranges from 0-14 Numbers 0-6 represent acids 7 is neutral Numbers 8-14 represent bases

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14strongest acid strongest base

pH ScalepH Scale As you move from pH 0 to pH 6, the concentration

of H+ DECREASES (10 times each number)

As you move from pH 8 to pH 14, the concentration of OH- INCREASES (10 times each number)

Ex: A substance with pH3 is 100 times stronger acid than a substance with pH 5. A substance with pH 8 is 100 times weaker base than a substance with pH 10.

pH calculationspH calculations pH is the negative logarithm of the hydrogen ion

concentration. pH = -log(H+)

What is the pH of a solution with a hydrogen-ion concentration of 4.2 X 10-10?

What is the pH of a solution with a concentration of (H+) = 0.045M?

pH calculations cont.pH calculations cont.

The pH of an unknown solution is 6.35. What is the hydrogen-ion concentration?

What is the hydrogen-ion concentration of a solution whose pH is 12.83?

pH indicatorspH indicators Indicators is a valuable tool for measuring pH

because its acid form and base form have different colors in solution.

Types of indicators: pH paper Bromophenol blue Methyl red Phenolphtalein