Chapter 4 - Electrolytes
An electrolyte is a
A nonelectrolyte may dissolve in water, but
Water is a good solvent for ionic compounds because it’s _____________
Negative ions are attracted to the positive hydrogen
Positive ions are attracted to the negative oxygen
Soluble Ionic Compounds (salts) Example Equation:
Molecular Compounds –
Acids
• An acid is usually a compound of hydrogen attached to something that looks like an anion
• Substances that increase the concentration of H+ when dissolved in water (Arrhenius).
•
Proton donors (Brønsted–Lowry).
Acids are molecular, therefore___________________________________
_______________________________________________________
There is a reaction that occurs between an acid and water:
H3O+ (hydrodium) is a water molecule with an extra proton (H+)
The acid is said to be ______________ (not dissociated)
Acids are considered electrolytes.
Many acids are _________________ (they have 1 hydrogen), but some have more than one.
Sulfuric acid is ___________and it ionizes in two steps.
Bases
• Usually a compound with a metal attached to the hydroxide ion.
−
• Substances that increase the concentration of OH when dissolved in water (Arrhenius).
• Proton acceptors (Brønsted–Lowry).
Summary
Soluble Ionic Compounds (Salts) dissociate into ions
Bases made of a metal attached to the hydroxide ion dissociate into ions (unless it is an
insoluble hydroxide)
Acids are ionized into H+ ions (H3O+) and anions
The base ammonia (NH3) is ionized into NH4+ and OH-
Strong Electrolytes
A strong electrolyte ionizes/dissociates completely when dissolved in water.
HCl  H+ + ClThe aqueous solution contains H+ and Cl- ions
Strong Electrolytes are:
There are only seven strong acids:
•
•
•
•
•
•
•
A cheer for strong acids: Hiber Hickle Hi, Hono Hickelo H2SO4!!!!!!!!!!!
(HBr, HCl, HI, HNO3, HClO3/HClO4, H2SO4)
(All other acids are weak!)
The strong bases are the soluble salts of the hydroxide ion
•
•
•
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(NH3 is a common weak base)
Weak Electrolytes
A weak electrolyte only dissociates/ionizes partially when dissolved in water.
+
The aqueous solution contains HC2H3O2, H , and C2H3O2
Sulfuric Acid again!
Sulfuric acid is diprotic and ionizes in two steps:
(strong)
(weak)
+
-2
A solution of H2SO4 contains H3O , HSO4 , and SO4
A little more on acids….
Hydrosulfuric acid usually comes out of the solution and into the gas phase (it smells like rotten
eggs!)
2HCl(aq) + Na2S(aq)  H2S(g) + 2NaCl(aq)
H2CO3(aq) is very unstable and decomposes to make H2O (l) and CO2(g)