1 / 5

The Mole We use a package for atoms and molecules called a mole A mole =

The Mole We use a package for atoms and molecules called a mole A mole = a. the number of Carbon atoms in 12 g of 12 C 6.022 x 10 23 units = Avogadro’s Number The amount of an element equal to its atomic mass 1 mole of natural C atoms weighs 12.01 g and has 6.022 x 10 23 atoms

jedidiah-braylon
Télécharger la présentation

The Mole We use a package for atoms and molecules called a mole A mole =

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 • We use a package for atoms and molecules called a mole • A mole = • a. the number of Carbon atoms in 12 g of 12C • 6.022 x 1023 units = Avogadro’s Number • The amount of an element equal to its atomic mass • 1 mole of natural C atoms weighs 12.01 g and has 6.022 x 1023 atoms • 1 mole of He atoms weighs 4.003 g and has 6.022 x 1023 atoms • 1 mole of Al atoms weighs 26.98 g and has 6.022 x 1023 atoms • Example: What is the mass of 6 Americium atoms? • Calculating moles, mass, and atoms • 1. Example: # atom / moles in 10g Al Cu I2 Hg Al Fe S

  2. C. A mole is the chemists “dozen” • A dozen marbles and a dozen peas both have 12 • A dozen marbles might weigh 100 grams • A dozen peas might weigh only 15 grams • 4. Example: 5.68 mg Si = ? atoms Si

  3. Empirical Formula = smallest whole number ratio of elements in the formula • I. Today’s Reaction • xZn(s) + yHCl(aq) --------> ZnxCly(aq) + H2(g) • Measured Mass excess Measured Mass • Safety • 6 M HCl can burn skin or put holes in clothes; wash off with water • H2(g) is flammable; do the reaction in the hood. • Use hot plate to boil off the extra water from the reaction • White fumes coming off dry solid is gaseous ZnxCly • Calculations (example) • 1.013g ZnxCly solid - 0.800g Zn(s) = 0.213g Cl in the compound • Change the mass of Zn and Cl to moles • Divide by the smallest number of moles; then round or multiply to whole #’s

  4. IV. Hints for determining empirical and molecular formulas • Convert mass % to grams of the element in 100 total grams of sample • Determine the Empirical Formula of an unknown if its Percent Composition is 47% Carbon, 47% Oxygen and 6.0% Hydrogen • Change these masses to moles by using the atomic mass of each element • Divide each number of moles by the smallest to get a small # ratio • Round off to a whole # if molar #’s are close to that whole number • Multiply the whole ratio by a factor to get all numbers to whole numbers • Multiply empirical formula by factor needed to give the correct molar mass • Molar Mass of unknown = 204.2 g/mol but C4H6O3 = 102.09 g/mol • Correct Molecular Formula: C4H6O3 x 2 = C8H12O6

  5. Incident: Mixing Acid with Water • Incident: Unrecognized Fume Hood Failure

More Related