1 / 13

Calculations The math of chem. rxns.

Calculations The math of chem. rxns. Mole. What is a mole, again?. A mole is a counting unit, like a dozen. 1 dozen eggs = 12 eggs 1 mole eggs = ? 6.022 x 10 23 eggs! A mole is the same, no matter if it ’ s counting eggs or atoms.

deva
Télécharger la présentation

Calculations The math of chem. rxns.

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. Calculations The math of chem. rxns. Mole

  2. What is a mole, again? • A mole is a counting unit, like a dozen. • 1 dozen eggs = 12 eggs • 1 mole eggs = ? • 6.022 x 1023 eggs! • A mole is the same, no matter if it’s counting eggs or atoms. • BUT it is SO large that the ONLY things we count with it are atoms and molecules!

  3. Would you like a mole of $?? • If I gave you one dollar a second, how long do you think it would take for me to give you a mole of dollars? (i.e. $6.022 x 1023) • It would take over 19,100,000,000,000,000 years. • The Earth was formed only 4,600,000,000 years ago! • A mole of dollars (each .0043 in thick) would reach over 7000 light-years!

  4. Calculate number of atoms in two mol Kr. • One mole = 6.02 x 1023 atoms • 2 moles = ? atoms 2 mol Kr x 6.02x1023 atoms Kr = 12.04x1023atoms 1 mol Kr

  5. 18.06 x 1023atoms He x 1 mol He = 3 mol He 6.02x1023 atoms He Calculate number of moles for 18.06 x 1023 atoms of He. • 6.02 x 1023 atoms = 1 mole • 18.06 x 1023 atoms = ? moles

  6. Molar Mass • Remember atomic mass? • Atomic mass of Na = 22.98977 g/mol • (22.99 grams of sodium per mole of sodium) • This is from the periodic table • Now, we learn molar mass: • What is the molar mass of NaCl? • 22.99 g/mol Na + 35.45 g/molCl (mass of Cl) • So, it is 58.46 g NaCl/molNaCl

  7. State the number of moles in 58.4 grams of Carbon. • 12.01 g C = 1 mol C • 58.4 g C = ? mol C • 58.4 g C x 1 mol C = 4.86 mol C 12.01 g C

  8. 12.04 x 1023 molec. x 1 mol H2O x 18.01 g H2O = 6.02x1023 molec. 1 mol H2O 36.02 g H2O 6.02x1023 molec. = 1 mol 12.04x1023 molec. = x mol 1 mol = 18.01 grams on Periodic Table x mol = y grams Calculate mass in grams of 12.04 x 1023 molecules H2O

  9. END

  10. atoms-mole-grams • To change atoms to grams OR to change grams to atoms, first calculate the number of moles. • atoms --> mol --> gram • OR • gram --> mol --> atoms • NO atom --> gram or gram --> atom

  11. Ex. Gram -> Mol -> Molecule • How many molecules are there in 1.0 grams of O2? • How many atoms is that? 1 mol O2x 32.00 g O2 6.02 x 1023molec. O2= 1 mol O2 1.0 g O2 x 1.9 x 1022 molec. O2

  12. Percent Composition • Sometimes, you have to calculate what percentage part of a compound is: • % part= part x 100% total • What percent of the total box is one strawberry? • 1/5 x 100% =20%

  13. Calculate % comp for Na2O2 • Mass Na (in Na2O2) = 2 x 22.99 g Na = 45.98 g Na • Mass O(in Na2O2) = 2 x 16.00 g O = 32.00 g O 77.98 g tot. • % Na = 45.98 g x 100% = 58.96% Na 77.98 g • % O = 32.00 g x 100% = 41.04 % O 77.98 g • (or 100% - 58.96% = 41.04% !)

More Related