1. Define the following:
2. List two physical separation methods.
3. List the formula for determining percent composition by mass.
Objectives: 1. to separate a three component mixture and
2. determine the percent composition by mass of each component in the mixture.
Materials: Ammonium chloride (NH4Cl), Sodium chloride (NaCl also known as table salt), and Silicon dioxide (SiO2 also known as sand)
Equipment: a variety of equipment is available at the supply table
Week One, Day 1: Make your mixture and separate it.
1. Mass a clean dry evaporating dish (preferably a larger one) and record this value in your data table
2. Make your own known sample:
A. Use a balance, spatula, and evaporating dish to measure all chemicals.
B. Place the evaporating dish on the balance and record the mass.
C. With the dish on the balance, press tare to rezero it (this disregards the mass of the dish and will give you the mass of the chemical only). Do this with each component of the mixture, but be sure to record each individual mass!
D. Use the following mass ranges for each component of your mixture:
NH4Cl between 0.10g and 0.20g
NaCl between 0.80g and 1.20 g
SiO2 between 0.80g and 1.20g
3. Place the dish on a hot plate and heat to sublime the NH4Cl. If possible, due this in a fume hood.
4. During the heating process gently stir the sample in order to facilitate the sublimation – white smoking. You will see the NH4Cl deposing on the stirring rod. This is fine because you will figure out the mass of NH4Cl by subtraction.
5. When the smoking has completely ceased, heat for two more minutes. CAREFULLY transfer the dish using crucible tongs to a wire gauze to cool.
6. Allow the sample to cool for at least 3 minutes and then mass the dish and remaining sample and