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Lecture 2

CHEM 235 Lecture Notes - Lecture 2: Ground Glass Joint, Filter Paper, Boiling Chip

Course Code
CHEM 235
Dana Zendrowski

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Benzoic acid
1. Weight the solid and record, place it and a boiling chip in 50 ml Erlenmeyer flask with ground
glass joint
2. Add 10 ml or less water to cover the solid
3. Add west condenser on the e.f, place it on hot plate, clamp the west condenser. Water in
bottom, water out- top
4. Heat the mixer and swirl the flask, if not dissolved add solvent via condenser
5. Add cork size 7, clamp the flask at 45 deg on the vertical poles
6. Wait 30 min for crystal to form (otherwise crystals forms in 5 min, add more solvent and reheat)
7. Suction filtration:
- Need suction trap, 125 ml filter flask, filter vac, Buchner funnel, small filter paper, glass rod
with rubber tip, spatula, watch glass, water solution
- Use 3 pronged clamp to attach the suction flask with the vertical rod
- Attach tube from suction trap to suction flask
- Add filter vac, Buchner funnel and a filter paper on the suction flask
- Wet filter paper with a bit of cold solvent
- Attach the tube to the aspirator and turn on full
- Unmount the tube before pouring the solution in s.f, use the glass rod to hold still the filter
- Reattach the tube, press down filter vac, use rubber tip to scrape out solvent or use the
mother liquor to rinse it out
- Use the suction to air dry the crystal for few mins
8. Use the spatula to take out the filter paper with crystals on the watch glass, let it dry and cover
it with weighing paper.
1. (AFTER STEP 4)Wait for the solution to cool down
2. Use a spatula to take out 0.5 cm of norit and celite, add it to the solution with a new boiling chip
3. (pre-HEAT e.f 50 ml and the filtering funnel for hot filtration) Add 1/4rth amount of solvent in
the e.f, bring the mixture to full boil
4. Hot filtration
- Need E.f, filtering funnel, fluted filter paper, glass rod with rubber tip, solution
- Attach a small ring to the vertical metal rod and place the funnel in it
- Place the e.f and adjust the ring to have a very narrow gap
- Place the fluted filter paper and use the glass rod to pour the solution
- Use rubber tube scrape down solvent or use mother liquid to rinse it out
- Dispose the solid in the unwanted solid waste container (CONTINUE TO STEP 5)
121.41 deg C
114.3 deg C
249.2 deg C
304 deg C
122.12 g/mol
135.17 g/mol
0.5 g
0.5 g
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