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Figure 3.1 Periodic Table. Equivalent Weight, EW. EW = MW/Z. Z = valence or charge. g/eq or mg/meq. Normality, N. N = (mass of material/L or solution)/ EW = number of equivalents/ L of solution. N = z X M. Chemical Reactions. Types of Reactions. Synthesis or combination reactions
E N D
Equivalent Weight, EW EW = MW/Z Z = valence or charge g/eq or mg/meq Normality, N N = (mass of material/L or solution)/ EW = number of equivalents/ L of solution N = z X M
Chemical Reactions Types of Reactions • Synthesis or combination reactions • A + B → C • Decomposition reactions • AB → A + B • 3) Single-replacement reactions • A + BC → AC + B • 4) Double-replacement reactions • AB + CD → AD + BC • 5) Combustion reactions • C3H8 + 5 O2 → 3 CO2 + 4 H2O
Consider the following reactions: → CaO(S) + H2O(l) Ca(OH)2(s) ← → 2 CaO(s) + 3 H2) + 2 PO43-(aq) Ca3(PO4)2(s) + 6 OH-(aq) ← Yielded by, formed from Reactants, products Subscripts s, l, aq Balanced reversible
Generalized reaction: ← aA + bB cC + dD → At equilibrium: [C]c [D]d K = [A]a [B]b
Stoichiometry Law of Conservation of Mass • Balancing Equations • Insure all products and reactants have proper formula • Identify most complicated compound. Asume there is only one of these in the equation. Balance the elementsw in this compound one at a time. • Focus initial attention on atoms present in the fewest compounds • Continue on a trial and error basis for the remaining compounds. Generally, balance the most prevelant atoms near the end. • Remove fractions and simplify to the smallest whole numbers possible.
Acid-Base Chemistry pH = - log [H+] pOH = - log[OH-] pH + pOH = 14 Acid – a compound that donates a hydrogen ion Base – a substance that accepts a proton (hydrogen ion) HA + B-→ A- + HB ← Acid Base Base Acid
Amphoteric compounds can react as either an acid or base → H2O + H2O ← HO- + H3O+ Acid Base Base Acid → H2O ← OH- + H+ [OH-] [H+] K = [H2O] Kw = [OH-] [H+] = 10-14
Dissociation Constant → HA H+ + A- ← [H+] [A-] Ka = [HA] BOH B+ + OH- [B+] [OH-] Kb = [BOH]
pKa = - log Ka pKb = -log Kb Ka X Kb = Kw = 10-14