Bell Ringer4-29-09

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Bell Ringer 4-29-09

1. When we balance equations, we only change
   _________, not subscripts.
2. T/F Balanced chemical equations should have the
   same number of atoms on each side of the arrow.
3. Chemical equations are just abbreviations using
   chemical _______ and numbers.
4. In 2C6H2O5, how many atoms of Hydrogen are there?

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ALCOS Objectives

• 1- Identify the steps of the scientific method
• 4 State the law of conservation of matter
  (Balancing Chemical Equations)

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Chapter 6 Section 3 Controlling Chemical
Reactions
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• To start a chemical reaction you need
  activation energy.
• Activation energy is the minimum amount of
  energy needed to start a chemical reaction.

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• Exothermic Reactions
• Endothermic Reactions
• P. 206 in textbook

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• Chemical reactions do not all occur at the same
  rate.
• Explosions ? really fast
• Rusting ? much slower

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Rate of Reaction

• Rate of reaction tells us how fast a reaction
  occurs.
• To find the rate of reaction, you can measure
  either how quickly the reactant is disappearing
  or how quickly the product is appearing.
• Ex. If it takes 1 minute for 2 inches of the
  candle to burn, how many minutes will it take for
  6 inches of the candle to burn.
• Ans. 3

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What affects the rate of reaction?

• Concentration- the amount of substance present.
• Surface area how big or small the area is or
  how much is being exposed
• Temperature hot or cold

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• Inhibitor slows down a chemical reaction. (ex
  food preservatives)
• Catalyst speeds up a chemical reaction. (ex
  enzymes)
• Ex. Enzymes breaks down food. Make it possible
  for your body to function properly.

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