Acid, bases and salts

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Slide 1

Acids, Bases & Salts

Slide 2

Terms

ACIDS are substances that form hydrogen ions (H+(aq)) when dissolved in water eg

Hydrochloric acid HCl gives H+(aq) and Cl-(aq) ions,

Sulphuric acid H2SO4 gives 2H+(aq) and SO42- ions

Nitric acid HNO3 gives H+(aq) and NO3-(aq) ions.

BASES are oxides and hydroxides of metals that react and neutralise acids to form salts and water only. Bases which are soluble in water are called alkalis. Not all bases fit into these categories e.g. ammonia.

Alkalis are substances that form hydroxide ions OH-(aq) in water eg

Sodium Hydroxide NaOH gives Na+(aq) and OH-(aq) ions,

Calcium Hydroxide Ca(OH)2 gives Ca2+(aq) and 2OH-(aq) ions.

Slide 3

In acid solutions there are more H+ ions than OH- ions.

In alkaline solution there are more OH- ions than H+ ions.

Acids that dissociate (ionize) to a large extent are strong electrolytes and Strong Acids.

Acids that dissociate only to a small extent are Weak Acids and weak electrolytes

Bases can be strong or weak depending on the extent to which they dissociate and produce OH– ions in solution. Most metal hydroxides are strong electrolytes and Strong Bases. Ammonia, NH3, is a weak electrolyte and Weak Base.

Slide 4

Basicity of Acid

It is the number of ionizable H+ ions present in an acid e.g.

HCl is mono basic, it ionizes to produce one H+ ion

HCl ============== H+ + Cl-

H2SO4 is Dibasic, It ionizes to produce two H+ ions.

H2SO4 =============== 2H+ + SO42-

H3PO4 is Tribasic, it ionizes to produce three H+ ions.

H3PO4 ============== 3H+ + PO43-

Slide 5

Acidity of a Base

It is the ionizable OH- ions present in an alkali. e.g.

NaOH is monoacidic

NaOH ========== Na+ + OH-

Ca(OH)2 is diacidic

Ca(OH)2 ============== Ca2+ + 2OH-

Slide 6

Common Strong Acids & their Anions

Slide 7

Common Weak Acids & their Anions

Slide 8

Naming of Acids

Binary Acids (H+ and a nonmetal)

hydro (nonmetal) -ide + ic acid

HCl (aq) = hydrochloric acid

Ternary Acids (H+ and a polyatomic ion)

(polyatomic ion) -ate +ic acid