BALANCING CHEMICAL EQUATIONS

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BALANCING CHEMICAL EQUATIONS
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Structure of an Equation Shows

• the reactants which enter into a reaction.
• the products which are formed by the reaction.
• the amounts of each substance used and each
  substance produced.
• Reactant Reactant --gt Product

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Conservation of Mass

• Matter is neither created nor destroyed,
  according to the law of conservation of mass .
• The number of atoms before and after a reaction
  does not change. Atoms are not lost.

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(Still conserving that mass!)

• Consider the following reaction
• Hydrogen Gas Oxygen Gas ? Water
• The formula for each molecule above is correct.
  However, it seems that we
• have gained an extra oxygen atom. This is not
  possible. Something is
• wrong.

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Balancing Chemical Equations

• Balancing this equation will satisfy the law of
  conservation of mass. See the solution above
• Hydrogen Gas Oxygen Gas ? Water

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An example of equation balancing

• Let's say I ask you the following thing on a
  test
• "Balance the equation that takes place when
  sodium hydroxide reacts with sulfuric acid to
  form sodium sulfate and water."
• How do we solve this?

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One methodDraw boxes around all the chemical
formulas.

• You're drawing those boxes so that you'll be sure
  not to mess around with the formulas to balance
  the equation.

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Make an element inventory

• In this inventory, your job is to figure out how
  many atoms of each element you have on the left
  and right sides of the equation.

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Balancing Equations

• Add coefficients to equations as needed.
• Do not change the formulas inside the boxes.
  That means count, but do not change subscripts.
• Final count of elements in reactants (before)
  must balance elements in product (after).

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Balance this!

• Magnesium Oxygen --gt Magnesium Oxide
• Mg O2 --gt MgO
• ?
• 2Mg O2 --gt 2MgO

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Balance This!

• Nitrogen Hydrogen --gt ammonia
• N2 H2 --gt NH3
• ?
• N2 3H2 --gt 2NH3

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Balance This!

• NaCl BeF2 --gt NaF BeCl2
• ?
• 2 NaCl BeF2 --gt 2 NaF BeCl2

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Balance This!

• CH4 O2 --gt CO2 H2O
• ?
• CH4 2O2 --gt CO2 2H2O

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Balance This!

• Mg Mn2O3 --gt MgO Mn
• ?
• 3Mg Mn2O3 --gt 3MgO 2Mn

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