1 / 13

The Mole & Chemical Formulas

The Mole & Chemical Formulas. A chemical formula represents the ratio of atoms that always exists for that compound Example: Water – H 2 O Always 2 H atoms to 1 O atom. The Mole & Chemical Formulas. This also means if you had a mole of water… You would have 2 moles of Hydrogen atoms

kovit
Download Presentation

The Mole & Chemical Formulas

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. The Mole & Chemical Formulas • A chemical formula represents the ratio of atoms that always exists for that compound • Example: Water – H2O • Always 2 H atoms to 1 O atom

  2. The Mole & Chemical Formulas • This also means if you had a mole of water… • You would have 2 moles of Hydrogen atoms • And 1 mole of Oxygen atoms

  3. Empirical Formula • This is the simplest ratio of atoms in a chemical formula. • Example: • Glucose, a sugar, has the molecular formula C6H12O6 • The empirical formula is CH2O

  4. Empirical Formula • Example: • A chemical has 80.0% C atoms and 20.0% H atoms. What is the empirical formula of the compound? • Use the %’s as masses to find moles…

  5. Empirical Formula 80.0 g C 1 mol C = 6.67 mol C 12.0 g C 20.0 g H 1 mol H = 20.0 mol H 1.0 g H

  6. Empirical Formula • Use the moles to determine the ratio: This is the Empirical Formula! 6.67 mol Carbon: = 1 6.67 mol C H3 20.0 mol Hydrogen: = 3 6.67 mol

  7. Molecular Formula • This gives the actual number of atoms for each element in a compound. • Example: • If the molar mass of the “CH3” compound from the previous problem is 30.0 g/mol, what is the molecular formula?

  8. Molecular Formula • Empirical formula mass for CH3 is 15.0 g/mol • Then find the ratio of molar to empirical mass. 30.0 g/mol (molecular) = 2.00 15.0 g/mol (empirical)

  9. Molecular Formula • Multiply the empirical formula by your new ratio: • C(1x2)H(3x2) = C2H6 (molecular formula)

  10. Molecular Formula • Example: • A chemical is 48.4% C atoms, 8.12% H atoms and the rest is Oxygen. If the molecular mass is 222 g/mol, find the molecular formula. • First find empirical formula…

  11. Molecular Formula 48.4 g C 1 mol C = 4.03 mol C 12.0 g C 8.12 g H 1 mol H = 8.12 mol H 1.0 g H 43.5 g O 1 mol O = 2.72 mol O 16.0 g O

  12. Molecular Formula 4.03 mol x 2 = 3 Carbon: = 1.48 C3 H6 O2 2.72 mol 8.12 mol x 2 = 6 Hydrogen: = 2.99 2.72 mol 2.72 mol x 2 = 2 Oxygen: = 1.00 2.72 mol

  13. Molecular Formula 222 g/mol (molecular) = 3.00 74.0 g/mol (empirical) C3x3 H6x3 O2x3 C9H18O6 Molecular Formula!

More Related