Understanding Moles and Avogadro Constant: Masses of Atoms and Molecules, Slides of Chemistry

Download Understanding Moles and Avogadro Constant: Masses of Atoms and Molecules and more Slides Chemistry in PDF only on Docsity! Fall 2016 – CH 6A mole & Avogadro constant Instructor: J.T.  The mole is the unit of measurement in the International System of Units (SI) for amount of substance.  It has the unit symbol “mol”.  Same as: [A dozen (doz) is a grouping of twelve entities.] Is analogous to saying: A mole is a grouping of 𝟔. 𝟎𝟐𝟐 × 𝟏𝟎𝟐𝟑 entities. Where: the Avogadro constant is: NA = 6.022 141 79 (30) x 1023 mol-1  By definition: A mole of 𝐶6 12 has exactly 12 grams mass. It means: 12 g of carbon-12 contains 𝟔. 𝟎𝟐𝟐 × 𝟏𝟎𝟐𝟑 atoms of carbon-12  By definition: One “atomic mass unit” = 1 12 mass of one atom of 𝐶6 12 Or: 1 atom of 𝐶6 12 weighs 12.000 amu, “u” 1) What is the mass of 1 atom of carbon? We know: 1 mole  6.022 × 1023 carbon atoms  12 g of carbon-12 𝑚𝑎𝑠𝑠 𝑜𝑓 1 𝑎𝑡𝑜𝑚 𝑐𝑎𝑟𝑏𝑜𝑛 = 12 𝑔 6.022 × 1023 = 1.993 × 10−23 𝑔 Note about the mole: i.e. Glucose: 𝐶6𝐻12𝑂6  1 molecule of glucose contains 6 atoms of C, 12 atoms of H, and 6 atoms of O  1 mole of glucose contains 6 moles of C atoms, 12 moles of H atoms, and 6 moles of O atoms.  10 moles of glucose contains 60 moles of C, 120 moles of H, and 60 moles of O atoms.  NA molecules of glucose contains 6 x NA atoms of C, 12 x NA atoms of H, and 6 x NA atoms of O.