Welcome! Wednesday 9/26

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Welcome!Wednesday 9/26

• Get out a sheet of paper for the warm up

2
Write the skeleton reaction for the following
(leave room between each question)

• 1. Hydrogen gas plus oxygen gas yields liquid
  water
• 2. Solid mercury II oxide yields mercury metal
  and oxygen gas
• 3. Solid iron II oxide plus hydrogen gas yields
  iron metal plus liquid water
• 4. Chlorine gas plus sodium metal yields solid
  sodium chloride plus heat

3
Balancing chemical equationsExample Magnesium
plus oxygen yields magesium oxide

• 1. Write out the balanced formulas for the
  reactants and the products (reactants on the left
  of the arrow, products on the right). Include
  states of matter, if given.
• Mg (s) O2 (g) ? MgO
• 2. Law of Conservation of Mass tells us what
  goes into a reaction must come out of the
  reaction start counting atoms on each side
• 1 mol Mg, 2 mol O ? 1 mol Mg, 1 mol O

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• 3. Use coefficients to balance
• 2Mg O2 ? 2 MgO
• Dont change subscripts once the formulas are
  written
• Look for polyatomics on both sides

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• Note Coefficients are MULTIPLIED by a subscript
• 2 O2 4 oxygen atoms

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• Heat may be a reactant or a product
• It is symbolized by ?
• Catalysts are symbolized above the arrow

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Balance

• 1. H2 (g) O2 (g)? H2O (l)
• 2. HgO (s) ? Hg (s) O2 (g)
• 3. FeO (s) H2 (g) ? Fe (s) H2O (l)
• 4. Cl2 (g) Na (s) ? NaCl (s) ? (heat)

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• 2 H2 (g) O2 (g)? 2 H2O (l)
• 2 HgO (s) ? 2Hg (s) O2 (g)
• Already balanced!
• Cl2 (g) 2Na (s) ? 2 NaCl (s) ? (heat)