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Catalyst – October 3+ 18, 2010 FUN GRAPH FRIDAY!
1. In what month do you think red light cameras were installed in Renton, WA?
2. What do you think happened to cause a decrease in citations (tickets) issued?
Red light cameras were installed in Renton, WA and this graph shows the number of citations issued each month.
Today’s Agenda
Catalyst Projects into Ms. Stroh Scavenger Hunt Notes College Presentation Exit QuestionGOOD LUCK TO ACT TAKERS!
Today’s Objectives
SWBAT begin to apply law of conservation of mass to chemical reactions by balancing chemical equations.
Whiteboard Practice
How many total atoms of each element are in these compounds?
AlCl3: Al = ? Cl = ?H2O: H = ? O = ?H2O2: H = ? O = ?KCl: K = ? Cl = ?
Be3S2: Be = ? S = ?NH4NO3: N = ? H = ? O = ?
Balancing equations RULES!
Key Point #1: When balancing equations, never, Never, NEVER change subscripts, only coefficients!
Coefficient
A coefficient is a whole number that comes in front of the compound formula, never in the middle!
You multiply the coefficient to all the numbers in the compound
2 AlCl3
Do you get it?
3 AlCl3 How many atoms of each element do they have?
3 Aluminum atoms 9 Chlorine atoms
Why is the top equation wrong?You figure it out (5 min) We never want to leave an equation
written like this… H2 + O2 H2O
We want to have it like this… 2 H2 + O2 2 H2O
WHY???
L-C-M!!!
Key Point #2: Chemical reactions MUST follow the Law of Conservation of Matter.What is the LCM? Matter cannot be created or destroyed. If 3 carbons are in the reactants of a
reaction, then there darn well better be 3 carbons in the products of a reaction.
Balancing Chemical Reactions
Try These:N2 + 3H2 2NH3
P4O10 + 6H2O
4H3PO4 Ca3P2 + 6H2O
3Ca(OH)2 + 2PH3