CHEM 0110 Chapter Notes - Chapter 3: Molecular Mass, Formula Unit, Chemical Formula
Document Summary
Molecular weight: sum of the atomic weights of all the molecules in a substance. Formula weight: sum of the atomic weights of all atoms in a formula unit of the compound. Mole: the quantity of a given substance that contains as many molecules or formula units as the number of atoms in exactly 12g of c-12. Mole refers to a particular number of things, like a dozen. Molar mass:the mass of one mole of a substance. 3. 3 determining chemical formulas/mass percentages from the formula. Mass%a=(mass of a in the whole/mass of the whole)x100. 3. 4: elemental analysis: percentages of carbon, hydrogen, and oxygen. You have a new substance you want the formula for. Burn it completely, as vapors pass through u tubes, a drying agent traps the h2o in one tube, eleminating h. another tube traps o. By weighing the tubes before and after, can determine how much was there, therefore composition of the formula of unknown substance.
