Chemistry: Week 7

At equilibrium, a solution contains [CH₃CO₂H] = 0.0787 M and [H3O+]=[CH3CO2−]=0.00118M. What is the value of K_a for acetic acid?

Substitution

How does the acid strength of compounds of hydrogen with nonmetals go as H-A bond strength decreases down a group in the periodic table?

Acid strength of binary compounds of Hydrogen with nonmetals increases as H-A bond strength decreases down a group in the periodic table

What happens across a row in the periodic table to the acid strength of Hydrogen compounds?

Across a row, the acid strength of binary compounds increases with increasing electronegativity of the nonmetal atom, since polarity of H- A bond increases

Table for increasing acid strength and increasing base strength

Ternary Compounds

A chemical compound composed of three different elements

• made of hydrogen, oxygen, and some third element “E”

• compounds may be acidic, basic, or amphoteric depending on properties of E atom

What happens if the central atom E has a low electronegativity in ternary acids and bases?

If the central atom, E, has a low electronegativity, its attraction for electrons is low

• Central atom doesn’t form a strong covalent bond with the oxygen atom and the bond between the element and oxygen is more easily broken than bond between oxygen and hydrogen

• Bond is ionic, hydroxide ions are released, and material is a base

What happens if the atom E has a high electronegativity in a ternary compound?

If E has a high electronegativity, it attracts the electrons it shares with oxygen and makes the bond covalent

• B is weakened because electrons are displaced towards E

• Bond b is polar and releases hydrogen ions to the solution, so material behaves as an acid