CHEM 143A Study Guide - Winter 2019, Comprehensive Final Exam Notes - Melting Point, London Dispersion Force, Vapor Pressure
8 May 2019
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Document Summary
Do chemistry using the things learned in 43a. No handouts in lab or on the bench. Crystals are special kinds of solid because they have a repeating structure. Purification is 95% or above week 1 page 1. When molecules start coming together we call it nucleation. With time, we see more and more molecules attach to the crystal. It"s slow and reversible so it is a great purification technique. Rapid precipitation means everything crashes out of solution immediately and so it is not pure. Need a highly saturated solution so you use a hot solvent. As it cools, concentration has to go down so you are forming a solid coming out of solution. Filter and recover week 1 page 2 (2) experiment 2. Objective experiment 0: identify and unknown through mixed melting point. Objective experiment 1: purify through recrystallization and identify through melting point, and hopefully mixed melting point. Sharp melting points shows that you have identified a pure compound.
