Question

Please use picture #1 to answer the chemistry questions in picture #2. Thank you

Calculate the theoretical yield of the aspirin. Show all work: 2.50x 180 aSpirin DATA TABLE for ASPIRIN: Mass of salicylic acid (g): Mass of filter paper (g): Calculated theoretical yield of &.So aspirin product: 3.26 Salycylic acid color with Fer FeCl, color tests Your aspirin color with FeCl: Dark pure - Part 2: Mass of acetylsalicylic acid (aspirin) after drying and filter paper Mass aspirin) Calculate your percent yield, show work: 2.36.35 experimental yield ()x 100 percent yield-theoretical yield () Observations (describe product, odors, anything else noteworthy): Dried aspirin Looked Crystalized Meltingpointtalwaysreport a124-О"c final(mdtndfil)at laut 121,2 C124.0 c What is the melting point range of your aspirin sample (how many degrees)? 28 c-124.0c) (Exp. 11, version 5) Page 8 of 10 will turn in only the Data, Post Lab Questions, and Concdlusions for this experiment What were the results of your FeCl, tests when you compared the aspirin you salicylic acid? made to the results of your melting point determination agree with the results from your FeCl, test? Explain. POST-LAB QUESTIONS 1. Give two physical properties you observed in your crude (unpurified) aspirin sample 2. If the theoretical yield of a reaction was yield for the reaction? Show formula and all work. calculated to be 3.11g and the actual yield was 2.65g, what was the percent 3. If a melting point range is 119.5c to 125.8°C, what can you say about the sample? Exp. 11, version 5) Page 9 of 10

Answer 1

In the FeCl₃ test with synthesized aspirin light purple color was observed whereas with salicylic acid dark purple color was observed.

This indicates that some unreacted salicylic acid is still present as an impurity (since the intensity of the purple color is less it can be concluded that salicylic acid is present in small amounts) with synthesized aspirin because pure aspirin will not show any color in the FeCl₃ test as it is acetylsalicylic acid and does not contain any Phenolic-OH group to react with FeCl₃.

Ans 2:

Since the melting point of pure aspirin is 135 ^oC and the observed melting point is in the range of 121.2-124 ^oC, it is evident that some impurity is present in the sample as impurities cause lowering of melting point. Most likely, some unreacted salicylic acid is present as an impurity and that's why it is showing less melting point and over a wide range (more than 2 ^oC range can be considered as wide). Thus it agrees to the observation from the FeCl₃ test.

1. Two physical properties are:

a. The Product is crystalline.

b. The melting point of the product is in the range of 121.2-124 ^oC.

2. Theoretical yield can be given as

Theoretical yield = moles of the product obtained/moles of the reactant taken (the limiting reactant i. e. 1 equivalent of which is taken in reaction)x 100 %

= (weight of the product obtained/molar mass of the product)/(weight of the reactant taken/molar mass of the reactant)x 100 %

= (W_p/M_p)/(W_r/M_r)x 100 %

= W_pM_r/M_pW_rx 100 %

If W_p = 3.11g, thenTheoretical yield = 100 %

If W_p = 2.65g, then % yield = 2.65g/3.11g x 100 % = 85.2 %

3. If the melting point is in the range of 119.5 to 125.8 ^oC, then the sample is surely impure because pure compounds show sharp melting points (within the range of 2 ^oC). The broad range of melting point is characteristic of impure compounds, impurity causes disruption of lattice forces and the sharpness at which crystal melts lost.