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9/26/1162 Chemical Equations

10/13/2015

61 Chemical Equations

10/13/2015

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Starter: ApplicationName the reactants in the following equations2Mg + O2 2MgOC + O2 CO2

2H2 + O2 2H2O

Name the products in the following equations2CO + O2 2CO2

N2H4 + O2 N2 + 2H2OC6H12O6 + 6O2 6CO2 + 6H2O

Connection: Balance/Unbalanced Ws

Exit:Write the equation for hydrogen and oxygen to water and label it Label: reactants, products, coefficients, subscripts, Chemical equation, elements, and compounds.

Practice: Notes: Paste Here

Identify the following molecule. Write the chemical formula and how many atoms of each element are in it.

EQ: How do chemical reactions obey the law of conservation of mass?

October 13, 2015

AGENDA8.5 E.

I will be able to investigate how

evidence of chemical reactions indicate

that new substances with different

properties are formed by reading, and

writing while completing notes and

activity

1 Starter2. Notes3. Activity 4. Exit

Starter

Identify the following molecule. Write the chemical formula and how many atoms of each element are in it. C6 H12 O6

Glucose

Date Lecture/ Activity/ Lab Page10/8 Practice Writing Chemical Formulas 57-5810/12 Writing Chemical Formulas 59-6010/13 Chemical Equations and the Conservation of Mass 61-62

Table of Contents

Chemical Equations & the Law of Conservation of

Mass

6H2O + 6CO2 C6H12O6+ 6O2

Water + Carbon Dioxide Sugar + Oxygen

Decide whether the following statements are physical changes or chemical changes.

A bicycle left out in the rain begins to rust.Chemical

A match burns, leaving only a charred stick of wood.Chemical

A copper wire is cut into five smaller pieces.Physical

An ice cube melts. Physical

Gasoline burns in a car engine. Chemical

Let’s review physical and chemical changes!

A spoonful of sugar is dissolved in a cup of coffeePhysical

A silver knife and fork tarnish when they are exposed to air for several weeks.Chemical

Leaves of a maple tree turn bright red as winter approaches. Chemical

Water is heated and changed to steam. Physical

Food is digested in your stomach.Chemical

• A chemical equation expresses what happens in a chemical reaction.

• Chemical Equations give us specific information about the substances involved in the reaction.

Law of Conservation of Mass

• Matter cannot be created nor destroyed; only changed.

• The same amount of matter that goes into a reaction comes out of the reaction.

• The chemical equation must be balanced to show that the reactants have the same amount of matter as the products.

• Sometimes a reaction produces a gas, which may be difficult to measure. However, if measured, the mass of the reactants will be equal to the mass of the products.

• Chemical reactions are written as:

Reactants Products

“Original stuff” “Yields” “new stuff”

CH4 + 2O2 CO2+2H2OMethane + oxygen yields carbon dioxide + water

The equation tells us how many atoms and molecules are involved.

2H2 + 2O 2H2O

4 hydrogen atoms

2 oxygen atoms4 hydrogen atoms

2 oxygen atoms

Reactants Products

In order to support the law of conservation, the equation must be balanced:

The number of atoms of each element to the left of the arrow.

Must equal the number of atoms of each element to the right of the arrow.

2H2 + O2 2H2O

H= H=O= O=

2 x 2= 4 2 x 2= 4

2 x 1= 22

The equation is balanced!

The atoms are just

rearranged.

To see if the equation is balanced, just count up the atoms of each element

2Ag + S Ag2S

Ag= Ag=S= S=

2 2

1 1

The equation is

balanced! The atoms

are just rearranged.

• The subscript is the small number to the right of the symbol. It tells you how many atoms are in each molecule. No number means 1.

• The coefficient is the large number in front of the molecule. It tells us how many of each molecule. No number means 1.

H2O

2H2O

• Remember that you can only change the coefficient to balance an equation

__Ag +__ H 2S __Ag2S +__H2

Ag= Ag= H= H= S= S=

1 2

2 2

1 1

2

/ 2

The equation is

balanced!

2H2O

III. APPLICATION• Name the reactants in the following

equations• 2Mg + O2 2MgO

• C + O2 CO2

• 2H2 + O2 2H2O

• Name the products in the following equations

• 2CO + O2 2CO2

• N2H4 + O2 N2 + 2H2O

• C6H12O6 + 6O2 6CO2 + 6H2O

.

9/26/1162 Chemical Equations

10/13/2015

61 Chemical Equations

10/13/2015

..

Starter: ApplicationName the reactants in the following equations2Mg + O2 2MgOC + O2 CO2

2H2 + O2 2H2O

Name the products in the following equations2CO + O2 2CO2

N2H4 + O2 N2 + 2H2OC6H12O6 + 6O2 6CO2 + 6H2O

Connection: Balance/Unbalanced Ws

Exit:Write the equation for hydrogen and oxygen to water and label it Label: reactants, products, coefficients, subscripts, Chemical equation, elements, and compounds.

Practice: Notes: Paste Here

Identify the following molecule. Write the chemical formula and how many atoms of each element are in it.

EQ: How do chemical reactions obey the law of conservation of mass?

V. EXIT

• Write the equation for hydrogen and oxygen to water and label it Label: reactants, products, coefficients, subscripts, Chemical equation, elements, and compounds.

• .