Chemical Reactions CHM 1010 PGCC Barbara Gage

Chemical Reaction Chemical change = chemical reaction Changes may be visible: color change cloudiness (precipitation) gas formed (bubbles and/or odor) reactant decreases (without dissolving) energy is released or absorbed CHM 1010 PGCC Barbara Gage

Chemical Equations Chemical changes can be written symbolically. The symbolic representation is called a chemical equation. Carbon reacts with oxygen to form carbon dioxide. C + O 2  CO 2 reactantsproducts CHM 1010 PGCC Barbara Gage

Chemical Equations Reaction arrows can go in either direction: 2 H 2 + O 2  2 H 2 O Or both directions: NH 4 OH  NH 3 + H 2 O CHM 1010 PGCC Barbara Gage

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Chemical Equations Because of the Law of Conservation of Matter, you must account for all atoms in a chemical change. Carbon reacts with oxygen to form carbon monoxide. C + O 2  CO 2 C + O 2  2 CO CHM 1010 PGCC Barbara Gage coefficient Equation is now balanced.

Chemical Equations A sample of propane, C 3 H 8, when ignited with oxygen produces carbon dioxide and water. C 3 H 8 + O 2  CO 2 + H 2 O C 3 H O 2  3 CO H 2 O CHM 1010 PGCC Barbara Gage

Chemical Reactions Al + O 2  Al 2 O 3 CaCO 3 + HI  CaI 2 + CO 2 + H 2 O Na 3 PO 4 + BaCl 2  NaCl + Ba 3 (PO 4 ) 2 C 4 H 10 + O 2  CO 2 + H 2 O CHM 1010 PGCC Barbara Gage

Chemical Equations If you have information on the states of matter, that can be added to the equation. s = solid l = liquid g = gas aq = aqueous Aqueous silver nitrate reacts with aqueous potassium chloride to form solid silver chloride and aqueous potassium nitrate. AgNO 3 (aq) + KCl (aq)  AgCl (s) + KNO 3 (aq) CHM 1010 PGCC Barbara Gage

Balancing Tips… Balance polyatomic ions that stay intact as a single unit. Leave hydrogens and oxygens to the last (oxygen very last) Be sure to reduce the coefficients to the smallest whole numbers. CHM 1010 PGCC Barbara Gage

Write the balanced chemical equation for the change in the boxes and indicate the reaction type. CHM 1010 PGCC Barbara Gage Before After

Let’s look at the lab rxns… Mg (s) + HCl (aq) > CuCO 3 (s) > Mg (s) > NaHCO 3 (s) + HCl (aq)-----> CuSO 4 (aq) + Fe (s) > CHM 1010 PGCC Barbara Gage

Let’s look at the lab rxns… CoCl 2 (aq) + Na 3 PO 4 (aq) –> KClO 3 (s) > Fe (s) > HCl (aq) + NaOH (aq) ----> CHM 1010 PGCC Barbara Gage

Mg (s) + 2 HCl (aq) > MgCl 2 (aq) + H 2 (g) CuCO 3 (s) > CuO (s) + CO 2 (g) 2Mg (s) + O 2 (g) > 2MgO (s) NaHCO 3 (s) + HCl (aq)---> NaCl (aq) + H 2 CO 3 (aq) ----> NaCl (aq) + H 2 O (l) + CO 2 (g) CuSO 4 (aq) + Fe (s) > Cu (s) + FeSO 4 (aq) 3CoCl 2 (aq) + 2Na 3 PO 4 (aq) –>Co 3 (PO 4 ) 2 (s) + 6NaCl (aq) 2KClO 3 (s) > 2 KCl (s) + 3 O 2 (g) 2Fe (s) + O 2 (g) > 2 FeO (s) HCl (aq) + NaOH (aq) ----> NaCl (aq) + H 2 O (l) CHM 1010 PGCC Barbara Gage

Types of Reactions 1)Combination or Synthesis elements or (element + compound) or compounds------> compound Fe (s) + S (s) >FeS (s) O 2 (g) + 2 CO (g) > 2 CO 2 (g) H 2 O (l) + SO 3 (g) > H 2 SO 4 (aq) CHM 1010 PGCC Barbara Gage

Mg (s) + 2 HCl (aq) > MgCl 2 (aq) + H 2 (g) CuCO 3 (s) > CuO (s) + CO 2 (g) 2Mg (s) + O 2 (g) > 2MgO (s) NaHCO 3 (s) + HCl (aq)---> NaCl (aq) + H 2 CO 3 (aq) ----> NaCl (aq) + H 2 O (l) + CO 2 (g) CuSO 4 (aq) + Fe (s) > Cu (s) + FeSO 4 (aq) 3CoCl 2 (aq) + 2Na 3 PO 4 (aq) –>Co 3 (PO 4 ) 2 (s) + 6NaCl (aq) 2KClO 3 (s) > 2 KCl (s) + 3 O 2 (g) 2Fe (s) + O 2 (g) > 2 FeO (s) HCl (aq) + NaOH (aq) ----> NaCl (aq) + H 2 O (l) CHM 1010 PGCC Barbara Gage

Types of Reactions 2)Decomposition or Analysis compound > elements or (element and compound) or compounds 2 HgO (s) -----> 2Hg (l) + O 2 (g) 2 KBrO 3 (s) -----> 2 KBr (s) + 3 O 2 (g) CaCO 3 (s) > CaO (s) + CO 2 (g) CHM 1010 PGCC Barbara Gage

Mg (s) + 2 HCl (aq) > MgCl 2 (aq) + H 2 (g) CuCO 3 (s) > CuO (s) + CO 2 (g) 2Mg (s) + O 2 (g) > 2MgO (s) NaHCO 3 (s) + HCl (aq)---> NaCl (aq) + H 2 CO 3 (aq) ----> NaCl (aq) + H 2 O (l) + CO 2 (g) CuSO 4 (aq) + Fe (s) > Cu (s) + FeSO 4 (aq) 3CoCl 2 (aq) + 2Na 3 PO 4 (aq) –>Co 3 (PO 4 ) 2 (s) + 6NaCl (aq) 2KClO 3 (s) > 2 KCl (s) + 3 O 2 (g) 2Fe (s) + O 2 (g) > 2 FeO (s) HCl (aq) + NaOH (aq) ----> NaCl (aq) + H 2 O (l) CHM 1010 PGCC Barbara Gage

Types of Reactions 3)Single Replacement element + compound > element + compound Cu (s) + 2AgNO 3 (aq) ---->2Ag (s) + Cu(NO 3 ) 2 (aq) CHM 1010 PGCC Barbara Gage

Mg (s) + 2 HCl (aq) > MgCl 2 (aq) + H 2 (g) CuCO 3 (s) > CuO (s) + CO 2 (g) 2Mg (s) + O 2 (g) > 2MgO (s) NaHCO 3 (s) + HCl (aq)---> NaCl (aq) + H 2 CO 3 (aq) ----> NaCl (aq) + H 2 O (l) + CO 2 (g) CuSO 4 (aq) + Fe (s) > Cu (s) + FeSO 4 (aq) 3CoCl 2 (aq) + 2Na 3 PO 4 (aq) –>Co 3 (PO 4 ) 2 (s) + 6NaCl (aq) 2KClO 3 (s) > 2 KCl (s) + 3 O 2 (g) 2Fe (s) + O 2 (g) > 2 FeO (s) HCl (aq) + NaOH (aq) ----> NaCl (aq) + H 2 O (l)

Types of Reactions 4) Double Replacement compound + compound —> compound +compound AgNO 3 (aq) + NaCl (aq) —> AgCl (s) +NaNO 3 (aq) Double Replacement Rxns: Solid forming AgNO 3 (aq) + NaCl (aq) —> AgCl (s) +NaNO 3 (aq) Gas-forming KHCO 3 (aq) + HCl (aq) ----> KCl (aq) + CO 2 (g) +H 2 O (l) Acid-Base HCl (aq) + KOH (aq) ----> KCl (aq) + H 2 O (l) CHM 1010 PGCC Barbara Gage

Mg (s) + 2 HCl (aq) > MgCl 2 (aq) + H 2 (g) CuCO 3 (s) > CuO (s) + CO 2 (g) 2Mg (s) + O 2 (g) > 2MgO (s) NaHCO 3 (s) + HCl (aq)---> NaCl (aq) + H 2 CO 3 (aq) ----> NaCl (aq) + H 2 O (l) + CO 2 (g) CuSO 4 (aq) + Fe (s) > Cu (s) + FeSO 4 (aq) 3CoCl 2 (aq) + 2Na 3 PO 4 (aq) –>Co 3 (PO 4 ) 2 (s) + 6NaCl (aq) 2KClO 3 (s) > 2 KCl (s) + 3 O 2 (g) 2Fe (s) + O 2 (g) > 2 FeO (s) HCl (aq) + NaOH (aq) ----> NaCl (aq) + H 2 O (l)

Types of Reactions 5)Oxidation-Reduction (redox) CH 4 (g) + 2O 2 (g) ----> CO 2 (g) + 2H 2 O (l) 2Mg (s) + O 2 (g) > 2MgO (s) 4HCl (aq) + 3FeCl 2 (aq) + KMnO 4 (aq) --> MnO 2 (s) + KCl(aq) + 3FeCl 3 (aq) + 2H 2 O(l) CHM 1010 PGCC Barbara Gage

Mg (s) + 2 HCl (aq) > MgCl 2 (aq) + H 2 (g) CuCO 3 (s) > CuO (s) + CO 2 (g) 2Mg (s) + O 2 (g) > 2MgO (s) NaHCO 3 (s) + HCl (aq)---> NaCl (aq) + H 2 CO 3 (aq) ----> NaCl (aq) + H 2 O (l) + CO 2 (g) CuSO 4 (aq) + Fe (s) > Cu (s) + FeSO 4 (aq) 3CoCl 2 (aq) + 2Na 3 PO 4 (aq) –>Co 3 (PO 4 ) 2 (s) + 6NaCl (aq) 2KClO 3 (s) > 2 KCl (s) + 3 O 2 (g) 2Fe (s) + O 2 (g) > 2 FeO (s) HCl (aq) + NaOH (aq) ----> NaCl (aq) + H 2 O (l)

Solubility Rules Reactants and products of reactions may be soluble. Use solubility rules to label them. CHM 1010 PGCC Barbara Gage

Solubility Rules Soluble Ionic Compounds All common compounds of Group IA (1) ions and ammonium ion are soluble. All common nitrates, acetates, and most perchlorates are soluble. All common chlorides, bromides, and iodides are soluble, except for those of silver (I), lead (II), copper (I) and mercury (I). All common fluorides are soluble except those of lead (II) and Group IIA (2). All common sulfates are soluble except those of calcium, strontium, barium, silver (I), and lead (II). Insoluble Ionic Compounds All common metal hydroxides are insoluble, except those of Group IA (1) and the larger members of Group IIA (2) (beginning with calcium). All carbonates and phosphates are insoluble, except those of Group IA (1) and ammonium ion. Most other combinations not mentioned above (such as chromates, oxides, sulfides) are insoluble, except those of Group IA (1) and ammonium ion. CHM 1010 PGCC Barbara Gage

Predicting Reactions… Complete and balance the following: copper(II) chloride reacts with sodium hydroxide CuCl 2 (aq) + NaOH (aq)  Double displacement reaction… CuCl 2 (aq) + NaOH (aq)  Cu(OH) 2 + NaCl CuCl 2 (aq) + 2 NaOH (aq)  Cu(OH) 2 (s) + 2 NaCl (aq) CHM 1010 PGCC Barbara Gage

Ionic reactions Ionic compounds in solution dissociate into ions. CuCl 2 (aq) + 2 NaOH (aq)  Cu(OH) 2 (s) + 2 NaCl (aq) Is actually… Cu 2+ (aq) + 2 Cl - (aq) + 2 Na + (aq) + 2 OH - (aq)  Cu(OH) 2 (s) + 2 Na + (aq) + 2 Cl - (aq) CHM 1010 PGCC Barbara Gage

Net Ionic Reactions Cu 2+ (aq) + 2 Cl - (aq) + 2 Na + (aq) + 2 OH - (aq)  Cu(OH) 2 (s) + 2 Na + (aq) + 2 Cl - (aq) Cu 2+ (aq) + 2 OH - (aq)  Cu(OH) 2 (s) net ionic equation CHM 1010 PGCC Barbara Gage

Net Ionic Reactions Lead (II) nitrate reacts with potassium iodide Pb(NO 3 ) 2 + KI  Pb(NO 3 ) 2 + KI  PbI 2 + KNO 3 Pb(NO 3 ) 2 (aq) + 2 KI (aq)  PbI 2 (s) + 2 KNO 3 (aq) Pb 2+ (aq) + 2 NO 3 - (aq) + 2 K + (aq) + 2 I -  PbI 2 (s) + 2 K + (aq) + 2 NO 3 - (aq) Pb 2+ (aq) + 2 NO 3 - (aq) + 2 K + (aq) + 2 I -  PbI 2 (s) + 2 K + (aq) + 2 NO 3 - (aq) Pb 2+ (aq) + 2 I - (aq)  PbI 2 (s) net ionic equation CHM 1010 PGCC Barbara Gage