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.

SCAVENGERHUNT!

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!

Yo, Ms. Stroh

What is a coefficient?

GOOD QUESTION!

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

How many of each atom do we have now?

7 AlCl34 H2O

6 H2O2

5 KCl2 Be3S2

4 (NH4)NO3

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

H2 + O2 H2O

__H____O__

Write down elements.

Balancing Chemical Reactions

H2 + O2 H2O

__H____O__

How many are there?

Balancing Chemical Reactions

H2 + O2 H2O

_2_H_2___O__

How many are there?

Balancing Chemical Reactions

H2 + O2 H2O

_2_H_2__2_O_1_

How many are there?

Balancing Chemical Reactions

H2 + O2 H2O

_2_H_2__2_O_1_

Get number equal!

Balancing Chemical Reactions

Try These:N2 + H2 NH3 P4O10 + H2O

H3PO4 Ca3P2 + H2O Ca(OH)2 + PH3

Balancing Chemical Reactions

Try These:N2 + 3H2 2NH3

P4O10 + H2O H3PO4

Ca3P2 + H2O Ca(OH)2 + PH3

Balancing Chemical Reactions

Try These:N2 + 3H2 2NH3

P4O10 + 6H2O

4H3PO4 Ca3P2 + H2O Ca(OH)2 + PH3

Balancing Chemical Reactions

Try These:N2 + 3H2 2NH3

P4O10 + 6H2O

4H3PO4 Ca3P2 + 6H2O

3Ca(OH)2 + 2PH3

COLLEGE PRESENTATION???

Exit Question

Balance the following equations:1. __KClO3 ---> __KCl + __O2

2. __S + __O2 ---> __SO3

Leave Notes in Folder Please!GOOD LUCK ACT TEST

TAKERS!!