Launch: 11/13   Grab your binder and immediately take a seat!

1.  How many of each atom are in the following molecules:

i.  Br2 ii.  H2S iii. CCl4

iv.  H2SO4 v.  C6H12O6

Announcements   Binder checks are worth a decent number of

points!

  It is really important that you   Do your launches

  Finish your homework (and get a stamp)   Make-up all work from absences

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What are chemical equations?

Mr. Heffner 11/13/09

  A chemical equation is…   a representation of a chemical reaction

2H2 + O2 2H2O

What are chemical equations?

Reactants Products

•  The substances that are produced (made) •  Right

•  The substances that react •  Left

  A chemical equation is…   a representation of a chemical reaction

2H2 + O2 2H2O

What are chemical equations?

Reaction Arrow

•  “turns into”

•  like an equals (=) sign

  A chemical equation is…   a representation of a chemical reaction

2H2 + O2 2H2O

What are chemical equations?

Coefficients Subscripts

•  Comes after the atom

•  Sub = below

•  Comes before the compound

•  distributed to all

Example 1.  How many H atoms does 2H2 have?

  multiply the subscript and the coefficient   Coefficient = 2

  Subscript = 2

  2 X 2 = 4 hydrogen atoms

Example 2.  How many H atoms does 2H2O have?

  multiply the subscript and the coefficient   Coefficient = 2

  Subscript = 2

  2 X 2 = 4 hydrogen atoms

Example 3.  How many O atoms does 2H2O have?

  multiply the subscript and the coefficient   Coefficient = 2

  Subscript = not there = 1

  2 X 1 = 2 oxygen atoms

Example 4.  How many O atoms does Mg(OH)2 have?

  multiply the subscript and the coefficient   Coefficient = not there = 1

  Subscript = 2

  1 X 2 = 2 oxygen atoms

Foldable   Make foldable and define terms. Draw an

illustration if necessary. 1.  Chemical equation 2.  Reactants 3.  Products

4.  Coefficient 5.  Subscript

6.  Chemical reaction 7.  Chemical bond 8.  Molecule/compound

Practice Question   Practice question handout

Exit Slip 1.  What are chemical equations?

a.  Representations of chemical reactions in which the reactants are listed to the left of a reaction arrow.

b.  Representations of chemical bonds in which 2 valence electrons are depicted by a straight line

c.  Representations of chemical reactions in which the. products are listed to the left of the reaction arrow.

d.  A way to show how reaction arrows turn into reactants.

Exit Slip HC2H3O2 + NaHCO3 NaC2H3O2 + H2CO3

2.  Which of the following correctly identifies all of the reactants in the above chemical equation.

a.  NaC2H3O2

b.  NaHCO3 c.  NaC2H3O2 and HC2H3O2 d.  HC2H3O2 and NaHCO3

Exit Slip 4Na + 4H2O 4NaOH + 2H2

3.  Which of the following identifies the coefficient for H2O in the above chemical equation?

a.  1

b.  2 c.  4 d.  8

Exit Slip 4.  How many C atoms are there in 3C2H4?

a.  2 b.  3

c.  5 d.  6

Exit Slip 5.  Which of the following identifies the correct

number of atoms in 3H2SO4? a.  3 H atoms, 3 S atoms, 3 O atoms b.  2 H atoms, 1 S atom, 4 O atoms c.  6 H atoms, 3 S atoms, 4 O atoms

d.  6 H atoms, 3 S atom, 12 O atoms

Homework   Finish practice question worksheet