Evaporation and Filtration Lab
Objective: Demonstrate the Law of Conservation of Mass and expose students to various
laboratory equipment and important lab procedures.
Procedure:
A. Evaporation
1. Place a clean, empty, 50mL beaker on a scale. Zero-out the scale by pressing “tare".
2. Using your scoop add about 5g ( 0.5g) of salt to the beaker. Record the amount of salt
used on your data sheet to the nearest 10th of a gram.
3. Determine the mass of your empty evaporating dish.
4. Add about 25mL of tap water to the salt in the beaker.
5. Stir the mixture with a clean stirring rod
6. Add this mixture to your evaporating dish.
7. Create your evaporation set-up like the one in the picture.
8. Put on your goggles and carefully light the burner. Adjust the flame if necessary.
9. After mixture begins to simmer, remove watch glass using crucible tongs. Be careful your
solution does not get so hot it begins to splatter. Adjust the flame as needed.
10. When dry, weigh the evaporating dish, with the precipitate, once cooled.
11. Re-heat for another 5 minutes. Allow to cool. Re-weigh and record.
12. If there is a change greater than 0.2g between your two heatings, repeat step #11.
13. You have now gathered all your data and are ready for clean-up. Wash the precipitate
down the drain, rinse your lab equipment and store them in your drawer and cabinet.
14. Return chemicals to the area designated by your teacher.
B. Filtration
1. Create a set-up like the one in the picture.
2. Fold filter paper like the diagram below.
3. Filter the 50mL of the mixture & record your observations.
4. Make sure your instructor signs off on your completion of this technique.
Clean up: Throw out your filter paper, dispose of the leftover mixture down the drain. Wash
all glassware. Clean your lab station and return equipment to your cabinet.
Evaporation & Filtration- Lab Data (include units used AND show your work)
Evaporation Data
1. Mass of salt used
__________
2. Mass of empty evaporating dish
__________
3. Mass of evaporating dish and contents __________
BEFORE heating
4. Mass of evaporating dish and contents __________
AFTER heating #1
5. Mass of evaporating dish and contents __________
AFTER heating #2
6. Mass of evaporating dish and contents __________
AFTER heating #3 (optional)
7. Mass of salt recovered
__________
Analysis
1. Explain why you were asked to re-heat the evaporating dish contents one or two times.
2. Explain the difference in your answers for Data #3 and Data #5 according to the Law of
Conservation of Mass.
3. Calculate your percent error using the formula in your textbook on page _______
4. Explain any errors you encountered in this experiment.
5. Explain how this experiment might change if you used a more shallow evaporating dish the
next time you conducted this experiment?
6. What did you observe by filtering the mixture?
Filtration
Teacher Signature
______ Satisfactory completion
Clean-up ______ Satisfactory completion