Question

1. How many moles are in 9.6 mL of acetic anhydride, density of 1.082? Give two significant figures. Given molecular weight: 102 g

2. As a "rule of thumb" there are 20 drops of a liquid in a mL. Using this estimate and a density of 1.685, how many moles are in 9 drops of 85 % by weight phosphoric acid? Give two significant digits. Given molecular weight: 98 g

3. Starting with 9.6 g of salicylic acid, how many grams of acetylsalicylic acid (theoretical yield) can be made? Assume salicylic acid is the limiting reagent and a one to one stoichiometry. Give two significant digits. Given mole

4. Starting with 2.8 mL of acetic anhydride with a density of 1.082, how many grams of acetylsalicylic acid (theoretical yield) can be made? Assume acetic anhydride is the limiting reagent and a one to one stoichiometry. Give two significant digits. Given molecular weight of acetylsalicylic acid: 180 g. Given molecular weight acetic anhydride: 102 g

5. What is the % yield of the reaction making 3.3 g of acetyl salicylic acid from 8.9 g of salicylic acid, 5.6 mL of acetic anhydride (density 1.082), and 10 drops 85 % weight phosphoric acid (density 1.685)? Use given molecular weights. Give two significant figures.

Answer 1

1) moles of acetic anhydride:

      mass of acetic anhydride = density x volume = 1.082 g/mL x 9.6 mL = 10.387 g

Given that molar mass of acetic anhydride= 102 g/mol

Therefore,

moles of acetic anhydride = mass of acetic anhydride/ molar mass of acetic anhydride

                                      = 10.387 g/ 102. g/mol

                                      = 0.1018 moles

Therefore,

0.1018 moles are in 9.6 mL of acetic anhydride.