The Law of Conservation of Mass

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The Law of Conservation of Mass
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Todays Warm-Up

• Here it goes again- the video
• We already know that digestion is both a physical
  and chemical change. Chewing breaks food into
  smaller pieces while digestion breaks and reforms
  chemical bonds, releasing energy for a variety of
  purposes- for example, running on a treadmill
• Or dancing and singing on a treadmill!

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Todays Warm-Up

• A bit of a brainteaser
• Called

The Prediction
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Todays Warm-Up

• Plop, plop, fizz, fizz BLAST-OFF!

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Todays Homework

• Lets do a quick grade of our Physical/Chemical
  Changes homework sheet
• Every blank is an answer- 3 pts each

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Law of Conservation of Mass

• Matter is neither created nor destroyed, just
  altered by physical or chemical changes.
• The mass of a block of wood the mass of the
  ash, gases and smoke particles
• No mass is lost or gained, just transformed

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Law of Conservation of Mass

• Changes in Matter- video intro
• Law of Conservation of Mass lab activity
• Work in groups of two
• Follow directions on lab handout
• Answer all related questions
• Turn in to bin when complete

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Chemical Equations
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Todays Warm-Up

• Lets see what Tim and Moby have to say about
  Chemical Equations!

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Chemical Equations

• Chemical equations are a way of showing a
  chemical reaction using chemical formulas and
  symbols
• Because of the Law ofConservation of Mass in
  allchemical reactions the endproducts must
  equal the initialreactants.

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Chemical Equations
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Chemical Equations

• This is an unbalanced equation (sometimes also
  called a skeleton equation). This means that
  there are UNEQUAL numbers at least one atom on
  each side of the arrow.
• Remember A balanced equation MUST have EQUAL
  numbers of EACH type of atom on BOTH sides of the
  arrow.

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Chemical Equations

• An equation is balanced by changing coefficients
  in a somewhat trial-and-error fashion.
• Only the coefficients can be changed, NEVER a
  subscript.
• The coefficient X subscript total of atoms.

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Chemical Equations
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Chemical Equations

• Helpful hints
• Look at the highest subscript first
• Save single elements for last

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Chemical Equations

• To the Computer Lab / Library!
• http//funbasedlearning.com/
• Classic ChemBalancer Game- easy
• Review ChemBalancer Game- medium
• Brain Boggle ChemBalancer Game- hard
• Ooohhh my head hurts.

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Chemical Reactions

• Homework sheet- balancing chemical equations
  and/or other practice worksheets!
• Maybe even out of the textbook!

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Today's activity that might result in candy being
given away

• Balancing chemical equations with dry-erase
  boards- a competition of brains and speed!!!

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Balancing Chemical Equations

1. C5H12 O2 ---gt CO2 H2O
2. Zn HCl ---gt ZnCl2 H2
3. S8 F2 ---gt SF6
4. C2H6 O2 ---gt CO2 H2O

C5H12 8O2 ---gt 5CO2 6H2O
Zn 2HCl ---gt ZnCl2 H2
S8 24F2 ---gt 8SF6
2C2H6 7O2 ---gt 4CO2 6H2O
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Types of Chemical Reactions

• Addition (synthesis) reaction
• Reactants combine to make compounds
• Compounds combine to form larger/more complex
  compounds

rust
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Types of Chemical Reactions

• Decomposition reaction
• A reactant breaks up into pieces
• Compounds are broken down in to simpler compounds
  or elements

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Types of Chemical Reactions

• Decomposition reaction
• A reactant breaks up into pieces
• Compounds are broken down in to simpler compounds
  or elements
• Examples
• The electrolysis of water
• Elephant toothpaste

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Elephant Toothpaste

• This experiment shows the decomposition of
  hydrogen peroxide catalyzed by potassium iodide.
• Materials
• tall graduated cylinder (at least 500 ml)food
  coloringDawn detergent30 hydrogen peroxide
  (H202)saturated solution of potassium iodide
  (KI)disposable glovessplint (optional)

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Elephant Toothpaste

• The rapid catalyzed decomposition of hydrogen
  peroxide produces O2 gas which forms a foam with
  the liquid detergent
• 2H2O2 (aq) ----gt 2H2O O2 (g)
• Definitely a chemical reaction!

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Types of Chemical Reactions

• Combustion reaction
• Hydrocarbons (look for H and C) burn in oxygen
  (O) to produce energy, water, and often CO2
• Examples include burning paper, your car burning
  gasoline, your body burning food

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Types of Chemical Reactions

• Single displacement reaction
• One element takes the place of another in a
  compound
• One element swaps places with another

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Types of Chemical Reactions

• Double displacement reaction
• Two elements take the place of another in a
  compound
• Elements in two compounds swap places

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Types of Chemical Reactions
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Types of Chemical Reactions

• Lets watch a quick video clip for review of the
  four types of chemical reactions

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Types of Chemical Reactions

• Electrolysis of water- a decomposition reaction
  2H2O 2H2 O2

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Law of Conservation of Mass
Notes
Questions Vocabulary words Formulas Main
Ideas Possible Test Questions
Notes
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Summary of the notes and information learned
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Types of Chemical Reactions

• Homework sheet- classifying chemical reactions
• Prepare for Review and short Test all about
  chemical reactions next class period!

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Make it a great day Mustangs!