2 A mole is a number (like a dozen) A mole is a number (like a dozen). Having this number of atoms allows us to easily convert atomic masses to molar masses.6.02 x 1023six point zero two times ten to the 23rd power
3 What is the actual mass of a C atom? 12 umaapprox. 2 x grams (protons and neutrons each weigh about 1.7 x10-24 grams)
4 Atomic masses do not convert easily to grams They can’t be weighed (they are too small)It is useful to associate atomic mass with a mass in grams. It has been found that 1 g H, 12 g C, or 23 g Na have 6.02 x 1023 atoms6.02 x 1023 is a “mole” or “Avogadro’s number”
6 1 dozen grains of rice = 0,21 g1,94 g of grains of rice contain1,94/0,21 = 9,2 dozen grains of rice
7 Comparing sugar (C12H22O11) & H2O Same1 gram each1 mole eachvolume?No, they have dif. densities.No, molecules have dif. sizes.mass?Yes, that’s what grams are.No, molecules have dif. massesN^ of moles?No, they have dif. molar massesYes.N^ of molecules?No, they have dif. molar massesYes (6.02 x 1023 in each)N^ of atoms?No, sugar has more (45:3 ratio)No
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