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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?

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Intro video: types of reactions

http://www.youtube.com/watch?v=i-HHvx1VC_8

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CHEMICAL REACTIONSCHEMICAL REACTIONS

Reactants: Zn + IReactants: Zn + I22 Product: Zn IProduct: Zn I22

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Chemical Chemical EquationsEquations

Their Job: Depict the kind of Their Job: Depict the kind of reactantsreactants and and productsproducts and and their relative amounts in a reaction.their relative amounts in a reaction.

44 Al Al (s)(s) + + 33 OO2 (g)2 (g) ---> ---> 22 AlAl22OO3 (s)3 (s)

The The numbers in the frontnumbers in the front are called are called

stoichiometric coefficientsstoichiometric coefficients

The letters (s), (g), and (l) are the The letters (s), (g), and (l) are the physical states of compounds.physical states of compounds.

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– Chemical reactions occur when bonds between the outermost parts of atoms are formed or broken

– Chemical reactions involve changes in matter, the making of new materials with new properties, and energy changes.

– Symbols represent elements, formulas describe compounds, chemical equations describe a chemical reaction

IntroductionIntroduction

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– Chemical equations show the conversion of reactantsreactants (the molecules shown on the left of the arrow) into productsproducts (the molecules shown on the right of the arrow).• A + sign separates molecules on the same

side• The arrow is read as “yields”• Example

C + O2 CO2

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

Parts of a Reaction Parts of a Reaction EquationEquation

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

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Activator:

Name the 5 types of reactions.

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Because of the principle of the Because of the principle of the

conservation of matterconservation of matter, ,

an an equation must be equation must be balancedbalanced..

It must have the same It must have the same number of atoms of the number of atoms of the same kind on both sides.same kind on both sides.

Lavoisier, 1788Lavoisier, 1788

Chemical EquationsChemical Equations

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• Solid (s)

• Liquid (l)

• Gas (g)

• Aqueous solution (aq)

• Catalyst H2SO4

• Escaping gas ()• Change of temperature ()

Symbols Used in Symbols Used in EquationsEquations

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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.

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– When balancing a chemical reaction you may add coefficients in front of the compounds to balance the reaction, but

you may notnot change the subscripts.

• Changing the subscripts changes the compound. Subscripts are determined by the valence electrons (charges for ionic or sharing for covalent)

Balancing EquationsBalancing Equations

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DIATOMIC ELEMENTS

• Elements that exist as 2 atoms naturally bonded together

• When by themselves in a reaction, they MUST have a 2 after their symbol

• Hydrogen, Oxygen, Nitrogen and all of the Halogens (Group 7A)

• H, O, N, + Halogens

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HANDOUT—SIDE B

1515Subscripts vs. Subscripts vs. CoefficientsCoefficients

• The subscripts The subscripts tell you how tell you how many atoms of many atoms of a particular a particular element are in a element are in a compound. The compound. The coefficient tells coefficient tells you about the you about the quantity, or quantity, or number, of number, of molecules of molecules of the compound.the compound.

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Chemical EquationsChemical EquationsChemical EquationsChemical Equations4 Al(s) + 3 O4 Al(s) + 3 O22(g) (g)

---> 2 Al---> 2 Al22OO33(s)(s)

This equation meansThis equation means

4 Al atoms + 3 O4 Al atoms + 3 O22 molecules molecules

---produces--->---produces--->

2 molecules of Al2 molecules of Al22OO33

AND/ORAND/OR

4 moles of Al + 3 moles of O4 moles of Al + 3 moles of O22

---produces--->---produces--->

2 moles of Al2 moles of Al22OO33

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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 Steps to Balancing EquationsEquations

1818Some Suggestions to Help Some Suggestions to Help YouYou

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

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2020Balancing Balancing EquationsEquationsBalancing Balancing EquationsEquations

___ H___ H22(g) + ___ O(g) + ___ O22(g) ---> ___ H(g) ---> ___ H22O(l)O(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.

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Balancing Balancing Equations EquationsBalancing Balancing Equations Equations

___ Al(s) + ___ Br___ Al(s) + ___ Br22(l) ---> ___ Al(l) ---> ___ Al22BrBr66(s)(s)2 3

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Balancing Balancing EquationsEquationsBalancing Balancing EquationsEquations

____C____C33HH88(g) + _____ O(g) + _____ O22(g) ---->(g) ---->

_____CO_____CO22(g) + _____ H(g) + _____ H22O(g)O(g)

____B____B44HH1010(g) + _____ O(g) + _____ O22(g) ---->(g) ---->

___ B___ B22OO33(g) + _____ H(g) + _____ H22O(g)O(g)

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Balancing EquationsBalancing EquationsBalancing EquationsBalancing EquationsSodium phosphate + iron (III) oxide Sodium phosphate + iron (III) oxide

sodium oxide + iron (III) phosphatesodium oxide + iron (III) phosphate

NaNa33POPO44 + Fe + Fe22OO33 ----> ---->

NaNa22O + FePOO + FePO44

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IPAD--Balancing Equations Practice

1.http://funbasedlearning.com/chemistry/chemBalancer/default.htm

2.https://www.khanacademy.org/science/mcat/physical-processes/stoichiometry/v/balancing-chemical-equations

3.http://chemistry.csudh.edu/lechelpcs/rxnbalancingcsn7.html

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Activator—WORD SPLASH

Write down as many words as you can think of that come to mind when you hear “chemical reactions”

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Activator: Balance these Rxns

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

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

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

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ACTIVATOR

• WHY MUST AN EQUATION BE BALANCED?

• WHAT ARE USED TO BALANCE EQUATIONS?

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ACTIVATOR

WHAT 3 TYPES OF REACTIONS WILL WE BE DOING IN LAB TODAY?

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EXTRA PRACTICE BALANCING

• http://chemistry.csudh.edu/lechelpcs/rxnbalancingcsn7.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?

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Activator

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LAB:

See purpose AND safety

FILL IN OBSERVATIONS/DATA (before and after each reaction)

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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)

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ACTIVATOR

QUICK WRITE:

Describe 2 chemical reactions that are taking place or have taken place around you today.

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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.

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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