Need help on questions 4 and 5 please! Questions 1. Describe the factors that co

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Need help on questions 4 and 5 please!

Questions 1. Describe the factors that could cause you to (b)By how much would this loss lower your obtain an incorrect melting point. percent yield? 2 Suppose the material that you are recrystalliz- ing fails to precipitate out of the cold solvent. What would you do to recover the material Solubility of salicylic acid in water TA·LE 4-1 from the solution? t is the white solid that quickly forms n the methyl salicylate is added to the Amount of salicylic acid per 100 mt waler sodium hydroxide solution? 0.10 013 0.23 0.63 1.8 3.7 Suppose that you obtain 1.0 g of salicylic acid from the hydrolysis of 1.3 mL of methyl salicy- 4. 10 25 late. Calculate your percent yield (a) Use Table 4.1 and the total estimated volume of solvent that you used for the recrystalliza- tion to calculate the amount of salicylic acid that would remain dissolved in the cold 5. 75 90 recrystallization solvent if you cooled it to 10°C before filtration.

Explanation / Answer

4. Ester hydrolysis of methyl salicylate generates salicylic acid. 1 mole of methyl salicylate produces 1 mole of salicylic acid.

Methyl salicylate: 1.3 ml was taken

Mass of 1.3 ml of methyl salicylate = 1.3×1.174 grams = 1.53 grams ( density = 1.174 g/ ml)

Molecular weight of methyl salicylate ( C8H8O3) is 152 g/ mole

So; no of moles of methyl salicylate used in reaction =

1.53/152 mole = 0.01 mole

So; 0.01 mole methyl salicylate will produce 0.01 mole salicylic acid (100% yield)

0.01 mole salicylic acid = 0.01 mole×138 g/mole = 1.38 grams

(Molar mass of salicylic acid is 138 g/ mole)

Experimental yield of salicylic acid = 1.3 g

Percent yield = (actual yield×100)/ theiretical yield

So; percent yield = (1.0×100)/1.38 % = 72.46%

5.The loss in yield = (theiretical yield - experimental yield) = 1.38-1.00 grams = 0.38 grams

At 10 0 C; 0.13 g of product is dissolved in 100 ml solvent

At that temperature; 0.38 g of product is dissolved in (0.38×100)/0.13 ml = 292 ml solvent

Estimated volume of solvent = 292 ml

B) percent yield is lowered by (100-72.46)% = 27.54%

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