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Empirical vs. molecular

Empirical vs. molecular. Empirical formula. Is the simplest form of a formula Is written in the lowest possible ratio E.g., CH 2 O or CH Will be reduced. May or may not exist in this form in the real world. Molecular formula.

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Empirical vs. molecular

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  1. Empirical vs. molecular

  2. Empirical formula • Is the simplest form of a formula • Is written in the lowest possible ratio • E.g., CH2O or CH • Will be reduced. May or may not exist in this form in the real world.

  3. Molecular formula • Is the true formula or actual ratio of the atoms in a compound. • E.g., C2H4O2 or C6H6 • Will not be reduced. Formula describes a substance as it actually exists.

  4. Empirical or Molecular? empirical & molecular • Na2O ___________________ • C3H6 ___________________ • K2SO4 ___________________ • C6H12O6 ___________________ molecular empirical & molecular molecular Keep in mind that for some compounds, its empirical formula can also be its molecular formula.

  5. Which pair has the same empirical formula? • Na2Oand Na2O2 • C6H12O6 and CH2O • C3H6 and C5H12 • C6H6 and C5H5

  6. Calculating an Empirical Formula • Determine the massof each element. • Convert the mass of each to moles.  • Find the moleto moleratiosof each element by dividing the number of moles of each element by the smallestnumber of moles. • If the ratio is not a wholenumber, multiply each ratio by a factor to make them all whole numbers. • Write the formula using the mole ratio as the subscriptfor the formula.

  7. Find the empirical formula of 69.5% O & 30.5% N. • Step 1: Divide % or grams by its atomic mass to get moles of each element. 69.5 g O 1 mol O 15.999 g O = 4.344 mole O 25.9 g N 1 mol N 14.007 g N = 2.177 mole N

  8. Find the empirical formula of 69.5% O & 30.5% N. • Step 2: Divide smallest mole number in each element to get ratio of that element. 4.344 mole O = 2 O 2.177 mole 2.177 mole N = 1 N 2.177 mole

  9. Find the empirical formula of 69.5% O & 30.5% N. • *This answer becomes the subscript for that element; round to nearest whole number if .8 or higher or lower than .2. Answer = NO2

  10. Independent Practice: 1. Analysis of a compound shows that it contains 10.88g of calcium and 19.07g of chlorine. Determine the empirical formula of this compound.

  11. Independent Practice: 2. One of the most commonly used white pigments in paint is a compound of titanium and oxygen that contains 5.99 g titanium by mass and 4.01 g oxygen by mass. Determine the empirical formula and name for this compound.

  12. Independent Practice: 3. Used in the production of nylon, adipic acid is an organic compound composed of 49.31% C, 43.79% O, and the rest is hydrogen. Determine the empirical formula of adipic acid.

  13. Calculating Molecular Formulas • The molecular formula will have the sameratioas the empirical formula. • To determine a molecular formula, we will multiplythe empiricalformulaby a whole number factor (WNF).

  14. Calculating Molecular Formulas

  15. 283.88 g/mol 141.943 g/mol 1. Empirical Formula = P2O5 Molar Mass= 283.88 g/mol What is the molecular formula of this compound? empirical mass = 141.943 g/mol WNF = = 2 (P2O5)2  P4O10

  16. 2. Nitrogen and oxygen form multiple molecular compounds together. One of these compounds is used to fuel space shuttles and has the empirical formula NO2. If the molar mass of this compound is 92.02 g/ mol, what is the molecular formula?

  17. Butane is commonly used in lighters. It is composed of 82.63% carbon and 17.37% hydrogen. It has a molar mass of 58.17 g/mol. What is the molecular formula of butane? **Fix typo in your packet, please.

  18. 4. Vitamin C is 40.91% C, 4.587% H, and the remaining is oxygen. If the molar mass of Vitamin C is about 180 g/mol, determine the empirical and molecular formula.

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