1

KWL CHART--REACTIONS

What do I

already

know about

chemical

reactions?

What do I

want to

know about

chemical

reactions?

What have

I learned

today about

chemical

reactions?

2

Intro video: types of reactions

http://www.youtube.com/watch?v=i-

HHvx1VC_8

3

CHEMICAL REACTIONS

_________: Zn + I2 _________: Zn I2

4

Chemical Equations

Their Job: Depict the kind of

_________ and ______ and their

relative amounts in a reaction.

4 Al (s) + 3 O2 (g) ---> 2 Al2O3 (s)

The numbers in the front are called

stoichiometric __________

The letters (s), (g), and (l) are the

________ states of compounds.

5

–Chemical reactions occur when bonds

between the outermost parts of atoms are

______ or _______

–Chemical reactions involve _______ in

matter, the making of ____ materials with

____ properties, and ________ changes.

–Symbols represent elements, formulas

describe compounds, chemical equations

describe a chemical reaction

Introduction

6

– Chemical _________ show the conversion of reactants (the molecules shown on the left of the arrow) into products (the molecules shown on the right of the arrow).

• A + sign separates molecules on the same side

• The arrow is read as “______”

• Example

C + O2 CO2

• This reads “carbon plus oxygen react to yield carbon dioxide”

Parts of a Reaction Equation

7

• The charcoal used in a grill is basically carbon. The ________ reacts with _______ to yield__________. The chemical equation for this reaction, C + O2 CO2, contains the same information as the English sentence but has quantitative meaning as well.

8

Activator:

Name the 5 types of reactions.

9

Because of the principle of the

__________________,

an equation must be ____________.

It must have the same

number of atoms of the

same kind on both sides.

___________ 1788

Chemical Equations

10

• ____________ (s)

• ____________ (l)

• _____________ (g)

• ________ solution (aq)

• ________ H2SO4

• Escaping ______ ()

• Change of ___________ ()

Symbols Used in Equations

11

Ticket out the Door

1. Name the 5 types of reactions.

2. How do you know a chemical reaction has

occurred?

3. Name 5 symbols that may be used in a

chemical equation.

12

–When balancing a chemical reaction you

may add _______________ of the

compounds to balance the reaction, but

you may not change the _________.

• Changing the subscripts changes the

compound. Subscripts are determined

by the valence electrons (charges for

ionic or sharing for covalent)

Balancing Equations

13

_____________ ELEMENTS

• Elements that exist as 2 atoms naturally

bonded together

• When by __________ in a reaction, they

MUST have a 2 after their symbol

• ___________________________________

___________________________________

• H, O, N, + Halogens

14

HANDOUT—SIDE B

15

Subscripts vs. Coefficients • The subscripts

tell you how many _______ of a particular element are in a compound. The coefficient tells you about the quantity, or number, of _________ of the compound.

16

Chemical Equations 4 Al(s) + 3 O2(g)

---> 2 Al2O3(s)

This equation means

4 Al atoms + 3 O2 molecules

---produces--->

2 molecules of Al2O3

AND/OR

4 _____ of Al + 3 _____ of O2

---produces--->

2 ______ of Al2O3

17

There are four basic steps to balancing a chemical equation.

1. Write the correct formula for the reactants and the products. DO NOT TRY TO BALANCE IT YET! You must write the correct formulas first. And most importantly, once you write them correctly DO NOT CHANGE THE FORMULAS!

2. Find the number of atoms for each element on the left side. Compare those against the number of the atoms of the same element on the right side.

3. Determine where to place coefficients in front of formulas so that the left side has the same number of atoms as the right side for EACH element in order to balance the equation.

4. Check your answer to see if:

– The numbers of atoms on both sides of the equation are now balanced.

– The coefficients are in the lowest possible whole number ratios. (reduced)

Steps to Balancing Equations

18

Some Suggestions to Help You Some Helpful Hints for balancing equations:

• Take one element at a time, working left to

right except for H and O. Save H for next to

last, and O until last.

• IF everything balances except for O, and

there is no way to balance O with a whole

number, double all the coefficients and try

again. (Because O is diatomic as an

element)

• (Shortcut) Polyatomic ions that appear on

both sides of the equation should be

balanced as independent units

19

20 Balancing Equations

___ H2(g) + ___ O2(g) ---> ___ H2O(l) 2 2

What Happened to the Other

Oxygen Atom?????

This equation is not balanced!

Two hydrogen atoms from a hydrogen

molecule (H2) combines with one of the

oxygen atoms from an oxygen molecule

(O2) to form H2O. Then, the remaining

oxygen atom combines with two more

hydrogen atoms (from another H2 molecule)

to make a second H2O molecule.

21

Balancing Equations

___ Al(s) + ___ Br2(l) ---> ___ Al2Br6(s) 2 3

22

Balancing Equations

____C3H8(g) + _____ O2(g) ---->

_____CO2(g) + _____ H2O(g)

____B4H10(g) + _____ O2(g) ---->

___ B2O3(g) + _____ H2O(g)

23

Balancing Equations

Sodium phosphate + iron (III) oxide

sodium oxide + iron (III) phosphate

Na3PO4 + Fe2O3 ---->

Na2O + FePO4

24

IPAD--Balancing Equations

Practice

1.http://funbasedlearning.com/chemistry/chem

Balancer/default.htm

2.https://www.khanacademy.org/science/mcat

/physical-

processes/stoichiometry/v/balancing-

chemical-equations

3.http://chemistry.csudh.edu/lechelpcs/rxnbalancingc

sn7.html

25

Activator—WORD SPLASH

Write down as many words as

you can think of that come to

mind when you hear “chemical

reactions”

26

Activator: Balance these Rxns

1. Fe + Ni(OH)2----- Ni + Fe(OH)3

2. AlBr3------- Al + Br2

3. C5H12 + O2------- CO2 + H20

27

ACTIVATOR

• WHY MUST AN EQUATION BE

BALANCED?

• WHAT ARE USED TO BALANCE

EQUATIONS?

28

ACTIVATOR

WHAT 3 TYPES OF

REACTIONS WILL WE BE

DOING IN LAB TODAY?

29

EXTRA PRACTICE

BALANCING

• http://chemistry.csudh.edu/lechelpcs/rxnbalancing

csn7.html

***I need to see when you are finished***

WATCH THE FOLLOWING VIDEO:

http://www.youtube.com/watch?v=i-

HHvx1VC_8

What chemicals did he use for each of the

reactions?

30

Activator

31

LAB:

See purpose AND safety

FILL IN OBSERVATIONS/DATA (before

and after each reaction)

32

LAB ASSIGNMENT:

Equations Section of Lab #1—7

(BALANCE AND WRITE NAMES OF

REACTANTS/PRODUCTS using your

“best friend” chart)

Conclusion Question #3 (BALANCE &

TELL TYPE OF RXN)

33

ACTIVATOR

QUICK WRITE:

Describe 2 chemical reactions that are taking

place or have taken place around you today.

34

BALANCING ACTIVITY

You will be with a partner. You and your

partner must EACH write down the

problems. You are to BALANCE AND

TELL TYPE OF RXN. When you think

you’re finished, let me check. Then you’ll

get your next card. The goal is to complete

as many questions as you can before time is

called.

35

Quiz--

QUIZ A: TELL TYPE FOR 1—20 (ALL)

BALANCE 1—10 ONLY –put

final coefficient ratio

QUIZ B: TELL TYPE FOR 1—20 (ALL)

BALANCE 11—20 ONLY—put

final coefficient ratio