Bell work 1/29/15

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Bell work 1/29/15

• True or False
• In a chemical equation, everything to the right
  of the arrow is the reactant.
• Justify your answer

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Student Learning Objectives

• SPI 0807.9.2 IDENTIFY THE COMMON OUTCOME OF ALL
  CHEMICAL CHANGES
• SPI 0807.9.3 CLASSIFY COMMON SUBSATNCES AS
  ELEMNTS OR COMPOUNDS BASED ON THEIR SYMBOLS OR
  FORMULAS
• SPI 0807.9.8 INTERPRET THE RESULTS OF AN
  INVESTIGATION TO DETERMINE WHETHER A PHYSICAL OR
  CHEMICAL CHANGES HAS OCCURRED.
• SPI 0807.9.10 IDENTIFY THE REACTANTS AND PRODUCTS
  OF A CHEMICAL REACTION
• SPI 0807.9.11 RECOGNIZE THAT IN A CHEMICAL
  REACTION THE MASS OF THE REACTANTS IS EQUAL TO
  THE MASS OF THE PRODUCTS (LAW OF CONSERVATION OF
  MASS)

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Study guide answers

1. What is an element? A substance that can not be
   separated or broken down into simpler substances
   by chemical means.
2. What is a chemical symbol? a shorter way to
   write an elements name.
3. What is a chemical formula? an easier way to
   write a molecule or compound
4. What is a chemical equation? an easier and
   shorter way to write a chemical reaction.
5. What is a reactant? what you start with in a
   reaction
6. What is a product? what you end with in a reaction

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Study guide answers

• Identify the following for each reaction
• 2 H2 1 O2 --gt 2 H2O
• CH4 2 O2 --gt CO2 2 H2O
• 2 H2O --gt 2 H2 1 O2
• Reactants Products
• 2 H2 1 O2 2 H2O
• CH4 2 O2 CO2 2 H2O
• 2 H2O 2 H2 1 O2

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Study guide answers

• 8. What is the law of conservation of mass?
  Mass can not be created or destroyed.
• 9. Why is the law of conservation of mass
  important to chemical equations? Because mass
  can not be created or destroyed, we have to
  balance a chemical equation.
• 10. What are the four clues that a chemical
  reaction may have taken place? 1. color
  change 3. solid formation
• 2. gas formation 4. energy change

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Study guide answers

• 11. What is a subscript? The small number behind
  the element's symbol the subscript tells how
  many atoms of an element in a chemical reaction.
  Ex H2 2 atoms of Hydrogen
• 12. What is a coefficient? The large number in
  front of a molecule the coeffient tells how
  many molecules you have applies to everything
  in the molecule. Ex. 3 O2 is three molecules of
  Oxygen

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Study guide answers

• 13. Balance Equations
• 2 Ag2O ? 4 Ag 1 O2
• 2_ NaBr 1 CaF2 ? 2 NaF 1 CaBr2
• 14. Be sure you know how to tell the number of
  atoms of each element in a molecule. Ex. NH3
  has 1 nitrogen atom and 3 hydrogen atoms for a
  total of 4 atoms.

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Study guide answers

• 15. What does it mean if a chemical symbol does
  not have a subscript? That there is only 1 of
  that atom in the formula.
• 16. For a chemical reaction to occur, what must
  happen (to the bonds)? Old chemical bonds break
  apart, atoms rearrange, and new bonds are formed.
• 17. You balance an equation by changing the
  coefficients, not the subscript!

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Balancing Equations Race

• Teacher will set up partners
• Each person will have a balancing equations sheet
  (You may want a separate piece of paper to work
  out the inventory)
• After you and your partner have balanced 5
  equations, bring them to me to check.
• Each partner must have the correct answers on
  their sheet to move on to the next set.
• The team with all the correct answers first wins
  5 Mendeleev dollars each.
• The second team wins 3 Mendeleev dollars each.
• The third team wins 1 Mendeleev dollar each.

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Exit Ticket

• When balancing an equation, I can only change the
  ____________.
• A. Reactant
• B. Product
• C. Coefficient
• D. Subscript