Daily TAKS Connection: Conservation of Mass

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Daily TAKS ConnectionConservation of Mass

• IPC(8) The student knows that changes in matter
  affect everyday life. The student is expected to
• (C) investigate and identify the law of
  conservation of mass

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Day 1 Construct a folded book foldable

• Instructions
• Hamburger fold the foldable handouts
• Cut 2 cm slits from the edges of the fold of the
  handout that has page 2 (as marked)
• Cut along the fold line of the other sheet of
  paper beginning and ending about 2 cm from each
  end (as marked).
• Burrito fold and insert paper from step 2 into
  the hole and open, forming a book.
• Color the front cover

• Construct a folded book foldable titled
  Conservation of Mass
• Materials
• Foldable handout (2 pages)
• Scissors
• Pen
• Colored pencils/crayons

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Day 2 Notes (record on page 1 of foldable)

• Notes
• atoms are neither created or destroyed in a
  chemical reaction
• atoms are rearranged in a chemical reaction
• Student Task Label the Reactants and the
  Products in the boxes provided above the
  diagram on page 1 of your foldable.

Image source http//www.iun.edu/cpanhd/C101webno
tes/matter-and-energy/images/h2o2.jpg
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Day 2 Notes continued (record on page 2 of
foldable)

• Rule
• to support the Law of conservation of mass, the
  mass of reactants must equal the mass of
  products

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Question

• If all the reactants in a chemical reaction are
  completely used, which of the following
  statements accurately describes the relationship
  between the reactants and the products?
• a. The products must have a different physical
  state than the reactants.
• b. The total mass of the reactants must equal the
  total mass of the products.
• c. The reactants must contain more complex
  molecules than the products do.
• d. The density of the reactants must equal the
  density of the products.

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Question
2H20 ? 2H2 O2

• The chemical equation shows H20 being decomposed.
  Which of these statements best describes the mass
  of the products if 150 g of H20 is decomposed?
• a. The mass of each product is equal to the mass
  of the H20.
• b. The sum of the products masses is 150 g.
• c. The sum of the products masses equals the
  mass of the H20.
• d. Both b and c.

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Question

• In the procedure shown, a calcium chloride
  solution is mixed with a sodium sulfate solution
  to create the products shown. Which of the
  following is illustrated by this activity?
• a. The law of conservation of reactants
• b. The law of conservation of products
• c. The law of conservation of mass
• d. The law of conservation of energy

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Day 3 Notes (record on page 3 of foldable)

• When a chemical reaction takes place and
• mass appears lost, a gas is probably a product
  and dissipates into the atmosphere
• mass appears gained, other atoms were
  introduced into the system and reacted with

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Question

• Which of these would support the idea that mass
  is conserved in a reaction that produces a gas as
  a product?
• a. Heating the reactants to ensure the reaction
  occurs in a gaseous state
• b. Subtracting the mass of the gas from the mass
  of the solid and liquid products
• c. Mixing the reactants and measuring their total
  mass
• d. Trapping the gas and measuring its mass

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Question

• The mass of a rusty nail is found to be slightly
  greater than the mass of the same nail before it
  rusted. The change in mass indicates that the
  rusting process
• a. is a physical change
• b. involves an energy-to-matter conversion
• c. decreases the density of the metal
• d. involves metal bonding with other atoms

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Question

• The illustrations show a conservation-of-mass
  experiment. The solution in the beaker lost mass
  because
• a. materials have less mass at high temperatures
• b. the mass of the reactants and products was
  less than 100 g
• c. sodium sulfate (Na2SO4) is lighter than air
• d. some of the water molecules turned into water
  vapor

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Day 4 Notes record on page 4 of the foldable

• List the atoms found in a chemical formula.
• an atom is indicated by an uppercase letter
• Example H Hydrogen
• OR
• an uppercase letter followed by a lowercase
  letter
• Example Hg mercury
• Determine the number of each atom type.
• Subscript multiplied by coefficient
• Example
• 2H20

H subscript 2 x coefficient 2 4 atoms total
O Subscript 1 x coefficient 2 2 atoms total
coefficient
subscripts
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Day 4 Student Task

• Determine the type and number of atoms in 2CH4
  and record on the table, page 4 of your foldable.

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Day 5 Notes (record on page 5 of foldable)

• To determine if a chemical equation demonstrates
  the law of conservation of mass, calculate the
  number/type of atoms for both the reactants and
  products (coefficient x subscript)
• Example
• 2Na MgF2 ? 2NaF Mg

Reactants Products
Na 2 Na 2
Mg 1 Mg 1
F 2 F 2
Because there are the same number of each type of
atom in the reactants and products, this equation
is balanced and supports the law of conservation
of mass.
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Day 5 Student Task

• Student task Determine if the equations below
  support the law of conservation of mass. Show
  your work on page 6 of your foldable.
• Cl2 KI ? 2KCl I2
• 4Na O2 ? 2Na2O
• 2Na HCl ? 2NaCl H2

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Day 6 Notes
Record the following steps on page 7 of your
foldable. Use these steps to balance the equation
shown. How to balance a chemical equation

1. Determine type/number of atoms for reactants and
   products. (type is always the same for both)
2. Choose an element that is not balanced.
3. Add a coefficient in front of the formula with
   that element and adjust your counts.
4. Repeat steps 2-3 until balanced.