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Bell RingerActive on SOCRATIVE

(room:crice)

OR

Grab a paper copy!

Turn it in to the tray and look over the Lab Procedure and

today’s notes.

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Chemical Reactions & Balancing Equations

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Chemical Reactions

2 Parts:

Reactants: substances at the start

Products: substances at the end

The reactants turn into the products.

Reactants Products

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Equation Format:

“+” means “reacts with” or “and”

“” means “yields” or “forms”

Reactants written on LEFT side

Products written on RIGHT side

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Inquiry Lab

Effervescent Tablet –Na(HCO3) & C6H8O7

NaHCO3+ C6H8O7 Na3C6H8O7 + H2O + CO2

sodium + citric sodium + water + carbon bicarbonate acid citrate dioxide

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In a Chemical Reaction The way atoms are joined is changed Atoms are neither created nor destroyed.

–This is the Law of Conservation of Matter

Balanced Equation: – Each element has same # of atoms on

both sides of the equation.

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C + O2 CO2

This equation is already balanced

– same number of atoms of each type of element on each side

What if it isn’t balanced already?

C + OO COO

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C + O2 CO

C + OCOO

• This is called a skeletal reaction

• Shows all the reactants and products

• Does not show balanced quantities

If it is NOT Balanced Already…

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Cooking Analogy for Chemical Reactions:

Skeletal reaction:

– Ingredients & description of meal Balanced reaction:

– Exact recipe

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C +O

COO

OC

• Add molecules until there is an equal number of atoms on both sides. • Use only molecules or atoms

already in the formulas• No new compounds used or

created• Start with the element you need

more of!

Skeletal Reaction Balanced Equation

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C +O

COO

OC

1C O2 2C & 2O

•The 2 subscript on Oxygen means there are 2 of them in the molecule.•Still not balanced need 1 more C on the reactant side.

Skeletal Reaction Balanced Equation

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C

+O

C

OO

OC

C

2C O2 2C & 2O

Equation:2C + O2 2CO

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C

+O

C

OO

OC

C

2C + O2 2COCoefficient:

•Large Number left of the compound formula.

•Represents the number of molecules/atoms• Helps to balance the equations • makes # of atoms on left side = # on

right side

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2C + 2O2 2CO2

2C 4O 2C & 4O•Notice the subscript only applies to the element it is next to!

• Coefficients & Subscripts on the same molecule

• The numbers must be multiplied to determine the number of atoms of that element.