Separation of a Mixture
(Purification of Polluted water)
A mixture is a physical blend of 2 or more substances. Mixtures can be separated using a variety
of methods. Heterogeneous mixtures with relatively large particles can be separated by filtration. In this
process, the mixture is poured through a filter which traps the largest particles.
Homogenous mixtures (solutions) must be separated by either chromatography or distillation, as in
this lab. Chromatography separates solutes by their different solubilities and molecular size. Distillation
separates the components of a solution by their different boiling points. The substance with the lowest
boiling point is separated first. The pure substance that is retrieved from a distillation is called the
Polluted water often contains a combination of large particles, which can be filtered, and very
small particles (like in a solution) which cannot be filtered.
To distinguish between a heterogeneous & homogeneous mixture
To separate the components of a mixture using filtration & distillation
Distillation apparatus Boiling stones “Polluted” water
Conductivity probe 2 100 mL beakers 125 mL flask
Gas burner striker
Wear chemical splash goggles throughout the entire experiment.
Tie hair back and secure loose clothing when working with an open flame.
1. Obtain 100 mL of “polluted water” from your instructor.
2. Record qualitative observations of the original sample.
3. Test the sample for conductivity and record the value.
4. Fold the filter paper as instructed and pour the sample through, collecting filtrate in a clean beaker.
(The filtrate is the solution that passed through the filter)
5. Record observations of filtrate and test for conductivity.
6. Add the filtrate and a boiling stone to a Florence or round-bottom flask attached to the
7. Once the filtration apparatus is assembled
as shown, wait for approval from the
instructor before starting the process.
8. Light the gas burner and collect the
distillate in a small flask/beaker.
9. IMPORTANT: Make sure the Florence
flask is not heated until dry, or breakage
could occur! (only collect enough for testing conductivity)
10. Record observations of distillate and test for
11. Clean up the lab area – be careful:
distillation apparatus is HOT.
Sample Observations Conductivity (S)
1. Describe the substance(s) separated in each step above.
2. Explain any changes to conductivity that were observed during the experiment.
3. Write a conclusion paragraph for this experiment:
a. Restate the purpose
b. Describe the results
c. Explain errors that may have occurred or limitations to the experiment
d. Suggest recommendations to eliminate the errors / limitations