Unit 4: Chemical Equations and Stoichiometry LESSON PLAN: 1. DQ 2. Balancing Equations

Balancing Equations reactants  products Remember the law of conservation of mass? When a chemical reaction occurs, no atoms are created or just destroyed – they are just rearranged Number of each element on the left side (reactants) must equal the number of the same element on the right side (products) reactants  products

Balancing Equations – The Steps! Write the unbalanced equation Ionic compounds: charges must add to zero Covalent compounds: use prefixes HOFBrINCl elements are diatomic when alone Example: hydrogen gas is written H2 Add phase if given: Solid = (s) Gas = (g) Liquid = (l) Aqueous (dissolved in water or solution) = (aq)

Example – Step #1 Lead (IV) sulfide solid + oxygen gas  Write and balance the following chemical equation: Lead (IV) sulfide solid + oxygen gas  lead (IV) oxide solid + sulfur dioxide gas

Balancing Equations – The Steps! Put coefficients in front of each substance to get the amounts on the left side = the right side Save hydrogen for 2nd to last Save oxygen for last Use the smallest whole number coefficients possible

Example – Steps #2 and 3 Lead (IV) sulfide solid + oxygen gas  Write and balance the following chemical equation: Lead (IV) sulfide solid + oxygen gas  lead (IV) oxide solid + sulfur dioxide gas

Balancing Equations Whiteboards Task One: Worksheet #1 problems 1, 3, 5, 7 Task Two: Worksheet #2 problems 1, 3, 5 Assignment: Worksheet #1 problems 11-15 Worksheet #2 problems 11-15

Balancing Equations Example #1 Now let’s balance this equation… __PbS2 (s) + __O2 (g)  __ PbO2 (s) + __SO2 (g)

Balancing Equations Practice #1 Write and balance the following chemical equation: iron metal + oxygen gas  iron (III) oxide solid

Balancing Equations Practice #2 Write and balance the following chemical equation: ammonium phosphate soln. + magnesium nitrate soln.  ammonium nitrate soln. + magnesium phosphate solid