Chemical Reaction Notes

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Chemical Reaction Notes
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Chemical Reaction Notes

• Known amounts of elements, polyatomic ions,
  and/or compounds can break apart, rearrange, and
  form ionic or covalent bonds in new compounds in
  order to increase stability and decrease the
  total amount of chemical potential energy.

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Chemical Reaction Notes

• These changes are called chemical reactions, and
  are different from the nuclear reactions we
  studied, which are when nuclei come together (or
  split apart) and create new atoms.

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Chemical Reaction Notes

• Chemists represent chemical reactions with
  equations.
• There are three types word, skeleton or chemical.

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Chemical Reaction Notes

• Chemical equations consist of a list of formulas
  for all of the reactants (compounds or elements
  added together to begin a chemical reaction) on
  the left side and a list of all of the products
  (compounds or elements which form during a
  chemical reaction) on the right side.

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Chemical Reaction Notes

• Reactants and products are separated by an arrow.
• Reactants are separated from one another by plus
  signs (as are products).

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Chemical Reaction Notes

• Each formula may be followed by a subscript
  (solid, liquid, gas, aqueous) to show what state
  of matter each compound is in.
• We may represent energy (heat, light, energy) as
  either a product or a reactant by writing it on
  the appropriate side of the equation.

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Chemical Reaction Notes

• Law of Conservation of Mass In a chemical
  reaction the arrangement of atoms will change,
  but the total number of each type of atom, and
  therefore the total mass, will remain constant.

http//nanopedia.case.edu/NWPage.php?pagechemical
.reactions
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Chemical Reaction Notes

• All chemical reactions must obey this law and
  therefore all chemical equations must obey it
  also.

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Chemical Reaction Notes

• In order to ensure that our chemical equations
  obey the law of cons. of mass, we balance all of
  our equations.
• To do this
• 1. You must make sure that all of the individual
  compounds formulas are correct.
• (Hydrogen, oxygen, nitrogen, and the halogens are
  all diatomic elements, meaning that whenever they
  are not found in a compound they form a molecule
  with themselves and have a formula with a
  subscript 2). Remember BrINCl HOF!

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Chemical Reaction Notes

• 2. Pick any number and place it as a coefficient
  in front of any compound.
• 3. You should then balance one element at a time
  from one side of the equation to the other by
  placing coefficients in front of the remaining
  formulas.

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Chemical Reaction Notes

• 4. Multiply coefficients to get rid of fractions
  if necessary.
• 5. Reduce coefficients if necessary.

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Chemical Reaction Notes

• Special hints
• 1. Never change your subscripts.
• 2. Balance elements that only appear in one
  formula on each side first.
• 3. After your first free choice of a
  coefficient, you must only use coefficients that
  balance the element.
• Count polyatomic ions as one unit.
• Balance the element oxygen last.
• Table Team Practice.

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Chemical Reaction Notes
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Chemical Reaction Notes
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Chemical Reaction Notes
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Chemical Reaction Notes
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Chemical Reaction Notes
Which of the following is NOT a chemical
reaction? A. a piece of wood burning B. a car
rusting C. an ice cube melting into water D. red
litmus paper turning blue
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Chemical Reaction Notes
What is the coefficient of bromine in the
equation 2Al(s) 3Br2(l) ? 2AlBr3(s)? A. 1
B. 2 C. 3 D. 6