Presentation on theme: "Unit 3. Chemical Reactions 3.3 How do we balance a chemical reaction?"— Presentation transcript:
1 Unit 3. Chemical Reactions 3.3 How do we balance a chemical reaction? February 8, 2010AIM: How do we balance chemical reactions in order to obey the law of conservation of mass?DO NOW: MR #3 An element that has a low first ionization energy and good conductivity of heat and electricity is classified as a(1) metal (3) nonmetal(2) metalloid (4) noble gasJCHOICELOW IONIZATION ENERGY?GOOD CONDUCTIVITY OF HEAT AND ELECTRICITY?METALNONMETALMETALLOIDNOBLE GASCheck the TABLE SLOWYESTHINK: copper wiresPeriodic Trends?HIGHNOSOME HIGH SOME LOWSOME YES SOME NOThese are nonmetals already….don’t waste your time!
2 HOW DO WE BALANCE EQUATIONS? C(s) + O2(g) → CO2(g)Step 1. Check that an equal amount of an elementappears in the reactants that does in the productsElementReactantsProductsC11O22Step 2. If not equal add coefficientsTHIS IS ABALANCEDEQUATIONStep 3. Check that the equation is balancedafter you add coefficients.
3 LET’S TRY SOME 2 x 2 = 4 2 x 2 = 4 2 1 x 2 = 2 H2(g) + O2(g) → H2O(g) ElementReactantsProductsHO2x 2= 42x 2= 421x 2= 2Not equal so we must add COEFFICIENTS!
4 LET’S TRY SOME 1 x 2 = 2 1 1 x 2 = 2 1 3 x 2 = 6 2 x 3 = 6 2 2 3 x 2 KClO3 KCl + O23ReactantsProductsKClO1x 2= 21x 2= 21x 2= 21x 2= 23x 2= 62x 3= 6
5 Complete the Independent Practice -IP will be collected at the end of class!!!WORK ON UNIT 1 in your HOMEWORK PACKETUNIT 1 completion will be check on Monday at the beginning of class
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