first two pictures are procedures done and third one is recorded data. questions
ID: 716829 • Letter: F
Question
first two pictures are procedures done and third one is recorded data. questions 1,2, and 3 please.
PROCEDURE Physical Properties of Organic Compounds 1. Melting point and recrystallization of aspirin ain 1.5 g of an impure sample of aspirin (acetylsalicylic acid). Pack a capillary tube that is closed on one end with 2-3 mm of the aspirin crystals. This by pressing the open end of the capillary tube into a mound of the verting and tapping the tube to pack in the solid, and dropping the t through a larger glass tube on the lab bench one h. Find the melting point of your sample using a melting point apparatus. The rate of heating should be 5-10° per minute until you approach the actual meltin temperature. At this point, the rate of heating should be slowed to 2-3° per minute. Since the aspirin is known to be impure, the heating pace should be slowed at about 100°C. Record the melting point. c. Begin this sequence by chilling about 3 mL of ethanol in an ice bath. This will be used in step e. Place the remaining impure aspirin crystals in a medium-size test tube. Add 4 mL of ethanol and heat until the solid dissolves. If necessary, filter out any solid that is left undissolved d. Let the solution cool to room temperature. If crystals do not form at room tempera- ture, carefully scratch the side of the test tube with a glass stirring rod to initiate their formation. When no more crystals appear to be forming, place the test tube in an ice bath for about 10 minutes. e. Vacuum filter the crystals using a Büchner funnel with a rubber adapter, a vacuum flask, a vacuum hose containing a trap, and a piece of filter paper. See Figure 2. Wash the crystals with the chilled ethanol and run the vacuum line until the crystals are com- pletely dry. (Overnight drying may be required.) f. Find the mass of the purified aspirin. Using the procedure described in steps a and b, determine the melting point of the purified aspirin. 2. Boiling point a semimicroscale procedure a. Using a graduated cylinder, measure 4 mL. of 1-butanol under the hood and pour it into a small test tube. Keep the test tube under the hood and clamp it onto a ring stand b. Add a small boiling stone to the test tube. Suspend a thermometer into the test tube approximately 2 cm above the level of the liquid.Explanation / Answer
1 )What is different between melting point value of aspirin before & after crystalization....
Answer : Before Recrystallization melting point of aspirin is 137. 1 to140.5 degree Celcies it is not match with standard melting point(135) of aspirin so it is impure material & after recrystallization it match with Standard melting point(135) that is 132.3 to 135 .8 degree Celcies . Melting point difference is due to impure & pure Aspirin...
2) Answer:- If we use 60 mL ethanol instead of 4 mL it's very large Quantity of solvent ethanol .So aspirin will dissolve completely but at the time of Chilling it will not precipitate again it will be in solution in dissolved form & Recrystallization not possible
3) Answer :-Ethanol Used for washing is chilling condition becose To avoid loss of Aspirin in washing Mother liqueur (WMLR)After filtration At withouts chilling loss of aspirin in (WMLR) will increase....
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