This is a recrystallization lab. Please help me with the following question:

Whats the purpose of the experiment?

identify the unknown compound and explain why?

calculate the percent recovery of the compound?

conclusion of the experiment?

The following attachments are the information required for the question.

here are the procedure of the experiment:

1) In a clean and dry test tube, weigh approximately 0.150 g (between 0.14 and 0.16 g) of your unknown sample. 2) In the fume hood set up your hot water bath: a. Fill a 100 mL beaker almost to the top with hot water from the tap. Add a few (3-5) boiling chips to the water. 0.150 g 3) Set up a supply of hot solvent (distilled water) for recrystallization. a. Fill a 50 mL Erlenmeyer flask with approximately 35 mL of distilled water. Add a few boiling chips. 4) Set the temperature control to mid-range value. Keep temperature below the boiling point of water. Distilled Water Tap Water Boiling Chips 5) While your water supplies are being heated, use your Pasteur pipette and graduated cylinder quickly determine the relationship between the volume to number of drops. 6) Set up your retort stand with a small three-pronged clamp and support the test tube containing your unknown solid on it. Add 1 mL of hot distilled water to the unknown sample. a. Stir the mixture with a glass rod and record your observations. Submerge your test tube into the hot tap water bath. 7) After you add 1 mL of hot solvent, reheated, and stirred the sample, determine if your unknown has completely dissolved. a. If your sample dissolved completely, add an extra 30 drops of hot solvent (keeping test tube in water bath), equilibrate the solution to bath temperature and stir the mixture. b. If your sample did not dissolve completely, add 0.5 mL of hot solvent (keeping test tube in water bath), equilibrate the solution to bath temperature and stir the mixture. Repeat this until it has dissolved. Once dissolved add 20 drops of water. 8) Once the temperature of your dissolved sample has equilibrated with the water bath, remove your test tube from the hot water bath. Leave it supported in the clamp, fit a cork stopper loosely in the mouth of your test tube, and allow your test tube to cool at room temperature, undisturbed. 9) As the saturated solution cools, crystals should form slowly. Record observations. a. When your test tube no longer feels warm to the touch, immerse it in an ice bath (ice mixed with a small volume of water). Secure your test tube to prevent its accidental tipping into the ice bath. b. Chill it for approximately 10 minutes before filtering the crystals. Also chill a supply of distilled water (in the plastic wash bottle). 10) While waiting for your mixture to cool, clean your collection of soiled glassware.

Section B. Isolation of crystals 1) Set up the apparatus for vacuum filtration (did you correctly include this scheme?). Remember to connect the filtration flask to a filtration trap that is attached to the vacuum line. Consult your TA if you are unsure. 2) Isolate the crystals on filter paper in a Bchner funnel. Rinse the crystals with a few drops of ice-cold distilled water: with vacuum disconnected, add just enough chilled solvent to wet the crystals completely, and reconnect the vacuum. Dry the crystals by leaving them in the funnel with vacuum connected, for approximately five minutes. 3) Weigh a clean, dry watch glass and record the mass. Without disconnecting the vacuum, remove the Bchner funnel from the filtration apparatus, and transfer the crystals to watch glass. Weigh the watch glass. Where do you record the mass? Why do we record the masses in this order? a. Calculate the percent recovery of your purified unknown solid and show it to your demonstrator before measuring its melting temperature.

Section C. Melting point measurement To identify your unknown sample, measure its melting point temperature and compare it with your list of literature values. You will take two melting point measurements of your sample. Operating instructions for the melting point instruments are provided in the Technique section. 1) Transfer a spatula-tip-full of your solid to a sheet of clean smooth paper (supplied by your TA) and use the flat surface of the spatula to crush the solid to a fine powder. 2) Pack a capillary with the finely powdered solid and measure its melting point temperature. Repeat with a new capillary tube to obtain a second sample. 3) Measure the melting point values for both of your samples 4) When you have completed all experimental work, and only after you have shown your purified unknown to the TA, dispose of the compound by adding it to the "solid wastes" container.

The unknown substances are benzoque acid, vanillin, phthalic acid, salicylic acid.

the data of my unknown substance is : initial color of white, initial mass 0.1522g. After step6 in section A nothing changed. In step 7 it dissolved after adding 20 more drops of distilled water. Mass of watch glass is 56.20g, weight after put the crystal on is 0.14. The melting point measured twice are: 217-224, 210-210.