1 / 12

Percentage Composition

Percentage Composition. Recall that the FORMULA WEIGHT [or molar mass] of a substance is the MASS IN GRAMS of ONE MOLE of particles of that substance. One mole contains 6.022 X 10 23 particles. This number is called AVOGADRO’S NUMBER .

adonica
Download Presentation

Percentage Composition

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. Percentage Composition

  2. Recall that the FORMULA WEIGHT [or molar mass] of a substance is the MASS IN GRAMS of ONE MOLE of particles of that substance. • One mole contains 6.022 X 1023particles. • This number is called AVOGADRO’S NUMBER.

  3. Within the mass of a mole of any compound, EACH ELEMENT contributes a CERTAIN PERCENTAGE to the OVERALL MASS. • We can calculate these percentages. This is known as PERCENTAGE COMPOSITION.

  4. Calculating Percentage Composition • Calculating Percentage Composition is easy: • 1. Find the FORMULA WEIGHT of the compound. • 2. Calculate the MASS PERCENTAGE of EACH ELEMENT in the compound.

  5. SAMPLE PROBLEM • Calculate the Percentage Composition of Potassium Cyanide, KCN. • 1. Find the FORMULA WEIGHT for KCN: • 1 K X 39.098 g = 39.098 g • 1 C X 12.011 g = 12.011 g • 1 N X 14.007 g = 14.007 g • Add Results  65.116 g/mol

  6. Now we will use the data from EACH ELEMENT to find the Percentage Composition: • 1 K X 39.098 g = 39.098g • 1 C X 12.011 g = 12.011g • 1 N X 14.007 g = 14.007 g • 65.116 g/mol • We will use the TOTAL MASS of EACH ELEMENT and divide it by the FORMULA WEIGHT, then MULTIPLY the results by 100%!

  7. Mass of K • %K = 39.098 g X 100% = 60.04% K • 65.116 g/mol • Formula Weight of KCN • %C = 12.011 g X 100% = 18.45 % C • 65.116 g/mol • % N = 14.007 g X 100% = 21.51 % N • 65.116 g/mol

  8. Finally, CHECK YOUR MATH! Add all the PERCENTAGES together….they should be VERY CLOSE TO 100%! • 60.04 % + 18.45% + 21.51% = 100%

  9. PRACTICE PROBLEM • Calculate the PERCENTAGE COMPOSITION of • Calcium Carbonate, CaCO3. • 1 Ca X 40.08 g = 40.08 g • 1 C X 12.011 g = 12.011 g • 3 O X 15.999 g = 47.997 g • 100.088 g/mol

  10. % Ca 40.08 g X 100% = 40.08% Ca • 100.088 g/mol • % C 12.011 g X 100% = 12.01% C • 100.088 g/mol • % O 47.997 g X 100% = 47.99% O • 100.088 g/mol • 40.08 % + 12.01% + 47.99% = 100.08% = 100%

  11. One Your Own • Find the Percentage Composition of Aluminum Phosphate, AlPO4. • ___ Al x ______ g = ________g • ___ P x ______ g = ________ g • ___ O x ______ g = ________ g • _______ g/mol 1 26.982 26.982 1 30.974 30.974 4 15.999 63.996 121.95

  12. 26.982 22.13 121.95 30.974 25.40 121.95 63.996 52.48 121.95 22.13 25.40 52.48 100.01 • % Al ________ x 100% = _______ %Al • % P ________ x 100% = _______ %P • % O ________ x 100% = ________ % O • ____% Al + ____% P + ____ %O = _____%

More Related