EXPLAINING DIFFERENCES/ EXPLAINING SIMILARITIES NATURE VS NURTURE.
6.4- Explaining Acids and Bases
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Transcript of 6.4- Explaining Acids and Bases
6.4- Explaining Acids and Bases
Arrhenius’ TheoryArrhenius’ Theory
acids ionize in water to produce hydrogen ionsbases dissociate in water to produce hydroxide ions
Arrhenius Theory WeaknessesArrhenius Theory Weaknesses
does not explain why: NH3(aq) acts as a base, or why CO2(g) can act as an acid some gases like sulfur dioxide and nitrogen dioxide produce acidic solutions
some substances act as both acids and bases
Revised Arrhenius TheoryRevised Arrhenius Theory
includes water in the reactionacids react with water to produce hydronium (H3O+
(aq))
HCl(aq) + H2O(l) ---> H3O+(aq) + Cl-
(aq)
hydronium is a hydrogen ion bonded onto a water molecule
..
bases are substances that react with water to produce hydroxide ions. This explains why ammonia acts as a base.
NH3(aq) + H2O(l) ---> OH-(aq) + NH4
+(aq)
also explains why molecules such as CO2(g), SO2(g), and NO2(g)
act as acids.Two step reaction:
CO2(g) + H2O(l) ---> H2CO3(aq)
H2CO3(aq) + H2O(l) ---> H3O+(aq)
+ HCO3-(aq)
also explains why some ions can act as both acids and bases.
eg. HCO3-(aq) and HPO4
2-(aq)
HCO3-(aq) + H2O(l) ---> H3O+
(aq) + CO32-
(aq)
HCO3-(aq) + H2O(l) ---> OH- (aq)+ H2CO3(aq)
Neutralization ReactionWe have seen neutralization reactions to look
like thisHCl(aq) +NaOH(aq) NaCl(aq) +H2O(l)
According to the modified Arrehius theory, we can now state that neutralization is the reaction between hydronium ions ( from the acid) and hydroxide ions ( from the base) to produce water
H3 O+ (aq) +OH- (aq) 2H2 O(l)
AssignmentRead page 248 -253Do page 251 #1,2Do page 253 #4,5,6