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Empirical formulas

QOD: If a bunch of cherries weighs 108 g, and one cherry weighs 12 g, how many cherries are there?. Empirical formulas. How do chemists figure out which atoms are in a molecule?. #7.7 Aim: How do we use mass to find molecular formulas ?. Molecular and empirical formulas.

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Empirical formulas

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  1. #7.7 Aim: How do we use mass to find molecular formulas? Agenda QOD (5) Lesson: molecular formulas (20) Activity: Find your match! (10) Closing (5) No HW QOD: If a bunch of cherries weighs 108 g, and one cherry weighs 12 g, how many cherries are there? Empirical formulas

  2. #7.7 Aim: How do we use mass to find molecular formulas? Agenda QOD (5) Lesson: molecular formulas (20) Activity: Find your match! (10) Closing (5) No HW How do chemists figure out which atoms are in a molecule?

  3. #7.7 Aim: How do we use mass to find molecular formulas? Agenda QOD (5) Lesson: molecular formulas (20) Activity: Find your match! (10) Closing (5) No HW #7.7 Aim:How do we use mass to find molecular formulas?

  4. #7.7 Aim: How do we use mass to find molecular formulas? Agenda QOD (5) Lesson: molecular formulas (20) Activity: Find your match! (10) Closing (5) No HW Molecular and empirical formulas A molecular formula tells exactly how many of each atom are in the molecule. An empirical formula tells the ratio of atoms in a molecule H : H H : C O H O H H O H H H O C C C C C C O H H O H H O H empirical formula of sugar = CH2O molecular formula of sugar = C6H12O6

  5. #7.7 Aim: How do we use mass to find molecular formulas? Agenda QOD (5) Lesson: molecular formulas (20) Activity: Find your match! (10) Closing (5) No HW How do we find a substance’s empirical formula? By dividing all subscripts by the same number. H H What is the empirical formula of H4S2O8? O O H O S O O S O H O O Divide all subscripts by 2 to get H2SO4

  6. #7.7 Aim: How do we use mass to find molecular formulas? Agenda QOD (5) Lesson: molecular formulas (20) Activity: Find your match! (10) Closing (5) No HW Which could be the molecular formula of the substance whose empirical formula is CH4? a. CH2 b. C2H8 c. C4H4d. C8H8 What is the empirical formula of the compound C12H24? a. CH2 b. C2H8 c. C4H4d. C8H8

  7. #7.7 Aim: How do we use mass to find molecular formulas? Agenda QOD (5) Lesson: molecular formulas (20) Activity: Find your match! (10) Closing (5) No HW Using mass to find molecular formulas: Mass mass of the empirical formula = “X” “X” the subscripts in the empirical formula = the molecular formula If the empirical formula is CH4O, and the mass of the whole molecule is 96 g, what is the molecular formula?

  8. #7.7 Aim: How do we use mass to find molecular formulas? Agenda QOD (5) Lesson: molecular formulas (20) Activity: Find your match! (10) Closing (5) No HW Activity:Find your match! • Pick a molecular or empirical formula from the jar • Find your match! (hint: if yours has a number, look for one with no number) Raise your hand when you’ve found it so Ms. B can check you off… 3) …to start the rest of your class-work: p. 41, #37 - 43

  9. #7.7 Aim: How do we use mass to find molecular formulas? Agenda QOD (5) Lesson: molecular formulas (20) Activity: Find your match! (10) Closing (5) No HW Closing: What is the empirical formula for C6H12O6?

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