Chemical Reactions The result of the chemical reaction is a new substance with unique physical and chemical properties. The result of the chemical reaction is a new substance with unique physical and chemical properties. Na (s) + Cl 2 (g) NaCl Reactants Products Reactants Products

Skeletal equation NaHCO 3 (s) + HCl (aq) NaCl (aq) + H 2 O (l) + CO 2 (g) yield sign yield sign (aq) aqueous (dissolved in water) (s) Solid precipitate (an insoluble solid) (l) Liquid (g) or gas heat is added heat is added

Remember 2Al 2 O 3 CoefficientSubscripts Coefficients will multiply by the subscripts To get total atoms of an element Al=2x2= 4 atoms of Al O=2x3= 6 atoms of O

Try Ca(NO 3 ) 2 How many Ca How many Ca How many NO 3 How many NO 3 How many N How many N How many O How many O 1 Ca (1x1) 1 Ca (1x1) 2 NO 3 (1X2) 2 NO 3 (1X2) 2 N (1x2x1) 2 N (1x2x1) 6 O (1x2x3) 6 O (1x2x3) Try 2Ca(NO 3 ) 2 How many Ca How many Ca How many NO 3 How many NO 3 How many N How many N How many O How many O 2 Ca (2X1) 2 Ca (2X1) 4 NO 3 (2x2) 4 NO 3 (2x2) 4 N (2x2x1) 4 N (2x2x1) 12 O (2x2x3) 12 O (2x2x3)

Balancing equations The number of each element in the reactants must equal the numbers of each element in the products. Only change coefficients, NOT subscripts. Only change coefficients, NOT subscripts. H 2 (g) + O 2 (g) H 2 O (l) H 2 (g) + O 2 (g) H 2 O (l) 2 H 2 2 H 2 2 O 1 2 O 1 H 2 (g) + O 2 (g) 2H 2 O (l) H 2 (g) + O 2 (g) 2H 2 O (l) 2 H 4 2 H 4 2 O 2 2 O 2 2H 2 (g) + O 2 (g) 2H 2 O (l) 2H 2 (g) + O 2 (g) 2H 2 O (l) 4 H 4 4 H 4 2 O 2 2 O 2

AgNO 3 + H 2 S Ag 2 S + HNO 3 1 Ag 2 1 Ag 2 1 N 1 1 N 1 3 O 3 3 O 3 2 H 1 2 H 1 1 S 1 1 S 1 2AgNO 3 + H 2 S Ag 2 S + 2HNO 3 2AgNO 3 + H 2 S Ag 2 S + 2HNO 3

Decomposition of hydrogen peroxide H 2 O 2 (l) H 2 O(l) + O 2 (g) H 2 O 2 (l) H 2 O(l) + O 2 (g)Balanced: 2H 2 O 2 (l) 2H 2 O(l) + O 2 (g) 2H 2 O 2 (l) 2H 2 O(l) + O 2 (g)

Stoichiometry 1 frame and 3 wheels are needed to create one tricycle If I use 1 dozen frames, how many tricycles can I make? If I use 1 dozen wheels, how many tricycles can I make? 1 dozen 4 or (1/3 dozen)

Stoichiometry 2AgNO 3 + H 2 S Ag 2 S + 2HNO 3 2AgNO 3 + H 2 S Ag 2 S + 2HNO 3 2 moles of silver nitrate yields 1 mole of silver sulfide Conversion Factor: 2 mole AgNO 3 = 1 mole Ag 2 S

2AgNO 3 + H 2 S Ag 2 S + 2HNO 3 How many moles of Ag 2 S will be produced from 3.5 moles of AgNO mole AgNO 3 x 1 mole Ag 2 S = 1.75 mole Ag 2 S 2 mole AgNO 3 2 mole AgNO 3