CHEMICAL EQUATIONS A chemical equation can be used to model a .

Parts of a chemical equation: reactants products

2Na + Cl2  2NaCl

arrow means “yields” or produces

Law of Conservation of (Matter)Mass

Matter cannot be created or destroyed in an ordinary chemical reaction.

This means the mass of the reactants must be equal to the mass of the products during a chemical change. Coefficients are used to balance chemical equations. Never change the subscripts to balance a chemical equation.

Count atoms to determine if a chemical equation is balanced:

H2O = 1 molecule of water, 2 atoms, 1 atom

3H2O = 3 molecules of water, 6 hydrogen atoms, 3 oxygen atoms

Examples

Reactants  Products Balanced (Yes or No) 1. CuS +Ca  CaS + Cu yes

2. CO  C + O no

3. S8 + O2  SO3 no

4. FeCl3 + 3NaF FeF3 + 3NaCl yes

Independent Work Directions: Determine the reactants and products in each chemical equation and tell if it is balanced or not. The first one has been done for you.

Chemical Equation Reactants Products Balanced? (Yes or No)

1. Na + Cl2 NaCl Na + Cl2 NaCl No____

2. C + O2  CO2 ______

3. C + O2  CO ______

4. C + H2  CH4 ______

5. H2O  H2 + O2 ______

Chemical Equation Reactants Products Balanced? (Yes or No)

6. Mg + 2O2  2MgO2______

7. H202  H2 O + O2 ______

8. 2NaCl  2Na + Cl2 ______

9. Fe + O2  Fe2O3 ______

10. Ca + Cl2  CaCl2 ______

Bell Ringer A day 11/, B day 11/ Question: What is the difference between a compound and a mixture? Answer: Compounds are made up of elements chemically combined. Mixtures are made up of substances not chemically combined.

Warm-up #11, A day 11/, Bday 11/ Question: How many atoms of each element are present in this compound? H2SO4 Answer: hydrogen: 2 sulfur: 1 oxygen: 4

Get out a Blank Sheet of Paper Place a heading in the TOP RIGHT CORNER Title: Counting Atoms, Item # 16.

Number your paper 1-5 and skip two lines between each.

Determine the number of atoms in each compound

Example: 5H2O hydrogen = 10; oxygen = 5 1. CaCO3 calcium = 1, carbon = 1, oxygen = 3

carbon=27, hydrogen=24, oxygen =12 2. 3C9H8O4

3. 5MgSO4 magnesium =5, sulfur = 5, oxygen=20

4. 8CH 4 carbon = 8, hydrogen=32

5. 3NaOCl = 3, oxygen =3, =3

Examples

Reactants  Products Balanced (Yes or No) 1. CuS +Ca  CaS + Cu yes

2. CO  C + O yes

3. S8 + O2  SO3 no

4. FeCl3 + 3NaF FeF3 + 3NaCl yes

Directions: Determine the reactants and products in each chemical equation and tell if it is balanced or not. The first one has been done for you.

Chemical Equation Reactant Products Balanced? (Yes or No)

1. Na + Cl2 NaCl Na + Cl2 NaCl No

2. C + O2  CO2______

3. C + O2  CO ______

4. C + H2  CH4______

5. H2O  H2 + O2______

Chemical Equation Reactants Products Balanced? (Yes or No)

6. Mg + 2O2  2MgO2 ______

7. H202  H2 O + O2 ______

8. 2NaCl  2Na + Cl2 ______

9. Fe + O2  Fe2O3 ______

10. Ca + Cl2  CaCl2 ______

Chemical Reactions and Equations 1. Photosynthesis (plants making glucose) carbon dioxide + water  glucose + oxygen

6CO2 + 6H2O  C6H12O6 + 6O2

2. Respiration (breathing) glucose + oxygen carbon dioxide + water

C6H12O6 + 6O2  6CO2 + 6H2O

Heating sugar

C12H22O11 + O2  CO2 + 11H2O + 11C

Warm-up , A day 11/16, B day 11/17 • Is the following equation balanced?

• S3 + O2  SO3 • Honors: If it is not balance, balance it. • Please take out your homework ws#11 Making Models of Molecules

• Carbon – Black • Hydrogen – White • Sulfur - • Oxygen – 4 prongs » Blue