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Do Now. If I have 1 dozen bagels, how many bagels do I have? _____ If I have 4 dozen bagels, how many bagels do I have? _____ If I have 0.5 dozen bagels, how many bagels do I have? _____ What weighs more: A pound of feathers or A pound of lead?. Day 1 - Notes. Unit: Chemical Quantities.
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Do Now • If I have 1 dozen bagels, how many bagels do I have? _____ • If I have 4 dozen bagels, how many bagels do I have? _____ • If I have 0.5 dozen bagels, how many bagels do I have? _____ • What weighs more: A pound of feathers or A pound of lead?
Day 1 - Notes Unit: Chemical Quantities History and Counting Representative Particles with the Mole
After today, you will be able to… • Using dimensional analysis, calculate how many atoms, molecules, or formula units are in one mole of that substance • Use correct significant figures and units in these calculations • Identify key scientists in the development of the mole
Substances can be measured in different ways…. • Count – 5 apples, dozen eggs • Mass – 2lbs of bananas, 16oz box of cereal • Volume – gallon of milk, pint of cream The Mole can be related to each of these types of measurements.
A Brief History on the Mole… Avogadro:(1811) An Italian scientist who studied the behavior of gases. Theorized:“The volume of a gas at a specific temperature and pressure contains equal numbers of atoms or molecules regardless of the nature of the gas.”
Loschmidt (1865): Estimated the average diameter of the molecules in air and was able to calculate the number of particles in a given volume of gas. Millikan (1910): Measured the charge on an electron. From the charge on a mole of electrons, he divided the two and obtained Avogadro’s number.
Perrin (1926): Earned the Nobel Prize for computing Avogadro’s number using many different methods and named this constant in honor of Avogadro. Used oxygen as a standard and proposed “Avogadro’s number is the number of molecules in exactly 32-grams of oxygen.”
The standard was later changed to the carbon-12 isotope. The presently accepted definition of the mole is: “The amount of any substance that contains as many elementary entities as there are in 12 grams of pure carbon-12.”
The mole (mol) as a unit in chemistry serves as a bridge between the atomic and macroscopic worlds. In Latin, mole means “huge pile.”
1 mole = 6.02x1023atoms, molecules, or formula units = 602, , , , , , , 000 000 000 000 000 000 000 = six-hundred and two sextillion
This equality can be used as a conversion factor to convert particles into moles, or moles into particles.
Example: How many atoms are in a 1.22 mole sample of sodium? K stands for what we know! U stands for what we are solving for! K: 1.22 mol Na U: ? atoms Na 1 mole = 6.02x1023atoms, molecules, or formula units 1.22 mol Na 6.02x1023 atoms Na x = 1 1 mol Na 7.34x1023 atoms Na
Example: How many moles are equal to 4.79x1024 molecules of CO? K: 4.79x1024molec. CO U: ? mol CO 1 mole = 6.02x1023atoms, molecules, or formula units 4.79x1024molec. CO 1 mol CO . = x 6.02x1023molec. CO 1 7.96 mol CO