CHEM 121 Lecture Notes - Lecture 4: Molar Mass, Chemical Formula, Mass Spectrometry

• School: Simon Fraser University
• Department: Chemistry
• Course: CHEM 121
• Professor: Steven Holdcroft

Document Summary

3: disclaimer: these notes, while detailed and covering every topic (that i believe is) of note, they are not all-encompassing. 3 percent composition of compounds: two types of percent composition, mass percent: expresses the mass of each element in the compound as a % of the total mass of the compound, e. g. mass percent of co2: 100% = 73: molar percent: expresses the number of moles/molecules of each element of the compound as a % of the total number of moles/molecules of the compound, e. g. molar percent of co2: 4 determining of chemical formula: 2 types of chemical formulae, molecular formula: exact # of atoms in a compound. From mass spectrometer: empirical formula: lowest integer ratio of atoms in a compound. 20 mol c 20 mol = 1 mol c. 80 mol h 20 mol = 4 mol h: empirical formula would then be ch4.