1. Chemical Formulas Chapter 20 and 21

2. Products and Reactants Reactant (s) Product (s) A (s) –solid + B (g) –gas C (l) –liquid + P ( aq)aqueous dissolved in water delta means change or difference, usually the reaction requires heating light –means requires light, sometimes ultraviolet sometimes visible Catalyst –a substance which speeds up a reaction without being consumed

3. Balancing Chemical Formulas H 2 g + O 2g 2H 2 O g Law of Conservation of matter says you must have all matter accounted for after a chemical reaction, so you must have all of the parts in the product that you began with in the reactants Reactants = 2Hs and 2Os total Products = 4Hs and 2Os, can’t be, doesn't have the same amount of Hs in the product and reactant. You can add more of the substance, but you can’t change the substance (can’t change small numbers) but you can change the numbers out in front (coefficients). So, add another molecule of water

4. Reactants Products H 2 +O 2 2H 2 O Hs OsHsOs 2 242 So Multiply H 2 x 2 (2 x 2 = 4) Then you would have 4 242 Means it is balanced

5. CH 4 g + O 2 g CO 2 g + H 2 Og C HOCHO 1 42123 Multiply H 2 0 x 2 on the product side 1 42144 Multiply 0 2 x 2 on the reactant side 1 44144 Balanced! So, CH 4 + 2O 2 CO 2 +2H 2 0

6. N 2 + 3H 2 NH 3 NHNH 2613 Multiply product x 2 2626 Balanced!

7. NH 3 + O 2 NO + H 2 O NHONHO 132122 Hint –make odd numbers even (Multiply NH3 x2 in the reactant) 2NH3 +O2 NO + H2O 262122 (Multiply H2O in product x 3) 2NH3 + O2 NO + 3H2O 262164 (Multiply NO x2 in the product) 2NH3 + O2 2NO + 3 H2O 262265 (Multiply O2 x 2 ½ in the reactant) NH3 + 2 ½ O2 2NO + 3 H2O 265265 Have to get rid of the fraction, so multiply everything x 2 4121041210 2NH3 + 5O2 4NO + 6H2O DONE!

8. Al 2 (SO 4 ) 3 + Ca(NO 3 ) 2 Al(NO 3 ) 3 + CaSo 4 Can’t break apart parenthesis. Polyatomic and stays in tack. Balance as a unit (none like this on test) AlSO 4 CaNO 3 AlSO 4 CaNO 3 23121113 Multiply AL(NO 3 ) 3 x 2 in product 23122116 Multiply Ca(NO 3 ) 2 x 3 in reactant 23362116 Multiply CaSO 4 x 3 in the product 23362336 Balanced So, Al 2 (SO 4 ) 3 + 3Ca(NO 3 ) 2 2AL(NO 3 ) 3 + 3CaSO 4

9. Types of reactions Exothermic reactions Reactants release heat during the reaction Less heat in product Very spontaneous Product + heat energy You would feel the heat given off from the reaction

10. Types of reactions Endothermic Reaction Absorbs heat during a reaction Keep pumping in heat to keep the reaction going More heat contained inside the products you would feel a cooler sensation because heat is being absorbed by the reactants

11. Types of reactions Combustion Reactions Ch 6 + 2O 2 CO 2 + 2H 2 O Carbon compound + O 2(g) CO 2(g) + H 2 O (g) Exothermic reaction Releases light and heat

12. Other types of Reactions none of this on test Combination A + B = AB two or more reactants = 1 product Decomposition AB = A + B one reactant = 1 or more products Single replacement A + BC = B + AC metal + ionic compound = a new metal and a new ionic compound Double replacement AB + CD = CB + AD two ionic compounds = two different ionic compounds