Practice: Which of the following compound(s) cannot be classified as an acid?
A. H2S
B. HCN
C. H2
D. C2H6
E. All are acids
Most acids have one common feature and that is the presence of the hydronium ion, which is represented by H+ or H3O+.
Concept #1: Identifying Binary Acids.
Binary acids can be identified by the fact that they all possess an H+ ion attached to an electronegative element.
Oxyacids can be identified by the fact that they all possess an H+ ion connected to a nonmetal and oxygen, hence the prefix “oxy”.
Concept #2: Identifying Oxyacids.
They are created by the hydration of nonmetal oxides.
Conversely, metal oxides create bases when hydrated by water.
Practice: Which of the following compound(s) cannot be classified as an acid?
A. H2S
B. HCN
C. H2
D. C2H6
E. All are acids
Concept #3: Acids and Electrolytes
Strong Acids are strong electrolytes that completely dissociate into ions when dissolved in water.
Weak acids are weak electrolytes that don’t completely ionize, but instead reach a state of equilibrium.
Concept #4: Strength of Binary Acids.
When looking at a binary acid we look at both electronegativity and size to determine their strength.
Practice: Which is the weakest acid from the following?
Practice: Which of the following acids would be classified as the strongest?
The strength of an oxyacid depends on the number of oxygen atoms and the electronegativity of the nonmetal.
Concept #5: The Strength of Oxyacids.
If your oxyacid has 2 or more oxygens than hydrogens then your oxyacid is a strong acid.
Concept #6: Comparing the Strength of Oxyacids.
When comparing the strengths of different oxyacids remember:
If they have different number of oxygens then the more oxygens the more acidic
If they have the same number of oxygens then the more electronegative the nonmetal the more acidic.
With some rules there are exceptions. Oxalic acid and Iodic acid have two more oxygens than hydrogens but are weak acids because carbon are iodine have low electronegativity.
Amphoteric species (compounds that can act as both an acid or a base) are also an exception to the rule for oxyacids.
Practice: Rank the following oxyacids in terms of increasing acidity.
a) HClO3
b) HBrO4
c) HBrO3
d) HClO4
Concept #7: Bases and Electrolytes.
Strong Bases are strong electrolytes that completely dissociate into ions when dissolved in water.
Weak bases are weak electrolytes that don’t completely ionize, but instead reach a state of equilibrium.
Bases are characterized by THREE major features: they may possess metals, they may have a negative charge or they may be an amine.
Concept #8: Bases and Group 1A.
Any Group 1A metal when combined with OH –, H –, O2– or NH2 – makes a STRONG BASE.
Concept #9: Bases and Group 2A.
Group 2A metals, from Ca2+ to Ba2+, when combined with OH –, H –, O2– or NH2 – makes a STRONG BASE.
Amines are compounds with only nitrogen or hydrogen (i,e. NH3) or with carbon, nitrogen and hydrogen (i,e. CH3NH2).
Concept #10: Amines.
Neutral Amines are considered weak bases.
Positive Amines are considered weak acids.
Example #1: Classify each of the following as a strong acid, weak acid, strong base or weak base:
a) HCHO2 c) H2NNH2
b) (CH3CH2)3NH+ d) HBrO3
Practice: Classify each of the following as a strong acid, weak acid, strong base or weak base.
Practice: Classify each of the following as a strong acid, weak acid, Strong base, or weak base.
Practice: Classify each of the following as a strong acid, weak acid, strong base or weak base.