1 A. Combination Reaction A + B AB i) SO 3 + H 2 O H 2 SO 4 ii) P + S P 2 S 5 iii) N 2 + H 2 NH 3 B. Decomposition Reaction AB A + B i) H 2 CO 3 H 2 O + CO 2 ii) KClO 3 KCl + O 2 C. Single Displacement Reaction: A + BC AC + B i) Zn + Cu(NO 3 ) 2 Zn(NO 3 ) 2 + Cu D. Combustion Reaction CxHy + O 2 CO 2 + H 2 O i) C 4 H 10 + O 2 CO 2 + H 2 O ii) C 6 H 12 O 6 + O 2 CO 2 + H 2 O Ea. Double Displacement Reaction: AB + CD AD + CB i) Ba(NO 3 ) 2 + H 2 S BaS + HNO 3 ii) MgCl 2 + Na 3 PO 4 Mg 3 (PO 4 ) 2 + NaCl Eb. Acid Base (Double Displacement) Reaction: HA + MOH H 2 O + MA i) HNO 3 + Ba(OH) 2 H 2 O + Ba(NO 3 ) 2 ii) Ca + H 2 O Ca(OH) 2 + H 2 ii) HCl + NH 4 OH H 2 O + NH 4 Cl 2
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Factors Towards Reactivity 1. Gas formation ZnS (s) + HCl (aq) ZnCl 2 (aq) + H 2 S (g) HNO 3(aq) + NaCN (aq) NaNO 3 (aq) + HCN (g) 2.. Weak Electrolyte or water formation (Neutralization) HI (aq) + Al(OH) 3 (s) H 2 O (l) + AlI 3 (aq) LiOH (aq) + HNO 3 (aq) LiNO 3(aq) + H 2 O (l) 3.Precipitation formation Pb(NO 3 ) 2 (aq) + NaCl (aq) NaNO 3 (aq) + PbCl 2 (g) MnS (s) + H 2 SO 4 (aq)???? 5 How can one predict if a precipitate forms when mixing solutions? Containing - Exceptions Containing - Exceptions Nitrates, (NO 3- ) Perchlorates (ClO 4- ) Acetates (CH 3 CO 2- ) None Carbonate (CO 3 2- ) Chromate (CrO 4 2- ) Phosphate (PO 4 3- ) Sulfides (S 2- ) Slightly soluble (for our purpose consider these insoluble) Halogens (X - ) X - = Cl -, Br -,I - Ag, Hg, Pb Hydroxides (OH-) Ca, Sr, Ba Alkali, NH 4 + Sulfates (SO 4 2- ) Alkali Grp1A, & NH 4 + Ca, Ba, Hg, Pb None 6
A) Molecular equation Mg(NO3)2(aq) + 2 KOH (aq) 2KNO3 (aq) + Mg(OH) 2(s) Mg+2 2 NO 3-2 K + 2 OH - 2 K + 2 NO 3 - Mg +2 2 OH- B) Complete ionic equaiton C) Net ionic equaiton 7 8
Dr. Fred Omega Garces Chemistry 200 Miramar College 9 10
11 What is the ph of a solution when an acid is mixed with a base? Stoichiometry Problem: HA H 3 O + + A- MOH OH + + M + MOH + HA H 2 O + MA Stoichiometry Problem: The amount of H 3 O + or OH - remaining after a portion is neutralize determines the ph of the solution. Analysis is a Stoichiometry problem only if a strong acid is combined with a strong base. 12
13 Rxn: NaOH OH 100% Net 20.00 ml HCl HCl H+ 100% H + + OH - H 2 O Conc H 3 O+: = 0.0982 mol OH- 18.34 ml 1 mol H+ 1 1 L 1mol OH- 20.00 ml [HCl] = 0.09005 M 18.34 ml NaOH @ end pt. 14
Some common acidbase indicators. The color changes occur over a range of ph values. Notice that a few indicators have two color changes over two different ph ranges. Mechanism for phenolphthalein indicator. At Low ph phenolphthalein is colorless and has a structure in which there is a five membered ring. In the presence of excess acid the five membered ring is broken and the resulting change in conformation gives rise to a compound which is pink. 15 Titration curve between strong acid and strong base. Analyte is HCl and titrant is NaOH. 16
Suppose you dissolve a 1.034 g sample of impure oxalic acid in some water, add an acid-base indicator, and titrant it with 0.485 M NaOH. The sample requires 34.47 ml of the NaOH solution to reach the equivalence point. What is the mass of oxalic acid, and what is its weight percent in the sample? 17 That a titration problem is nothing more than a Stoichiometry problem. Vol ( L) Liquid phase Density (g / cc) # of molecules / atoms N Av (6.02 10 23 ) particle (atomic) phase # of molecules / atoms N Av (6.02 10 23 ) particle (atomic) phase Vol (L) Liquid (l) phase Density (g / cc) Mass (g) Conc. (mol / L ) Vol (L) Pressure (atm) Temperature (K) Volume (L ) Molar Mass (g / mol) Solid phase Aqueous phase Gas phase Balance equation Moles A Moles Stoic. coefficient. B R (.0821 atm L ) mol K Molar Mass ( g / mol) Solid phase (g ) Gas phase R (.0821 atm L ) mol K Aqueous phase Mass (g) Conc. (mol / L) Vol (L) Pressure ( atm ) Temperature ( K) Volume ( L ) 18
Understand the Basic idea of a Chemical Reaction. Write and Balance a Chemical Reaction. Recognize the different chemical reactions. Combination Decomposition Single Displacement Combustion Double Displacement Driving force: i) weak electrolyte, ii) gas iii) precipitation Double Displacement (Neutralization) 19