CHEM 1A03 Lecture : Chem 1A03 FULL notes

• School: McMaster University
• Department: Chemistry
• Course: CHEM 1A03
• Professor: Jeff Landry

Document Summary

Systematic error: reading meniscus from sides and not middle like it"s supposed to be read, poor calibration, accuracy limits, poor use of equipment (no zeroing balance) Random error: equal probability of reading being too high/low, variations in glassware volume b/c temp. Increasing trials increased precision less random error. Precision how close measurements of same trial are. Accuracy - how close measurements are to actual. Absolute uncertainty: 1 sig dig, rounded to same place as last calculated digit. Atomic mass mass of atom of specific element. Expressed in amu (atomic mass units: ar relative atomic mass = in comparison to c12 12 amu, no units b/c avg of all isotopes of element. Molecular mass sum of masses of molecule: mr relative molecular mass = in comparison to c12 no units. Empirical formula: simplest ratio of atoms in compound. Molecular formula: multiple of empirical formula, contains whole number of empirical formulas.