##### Stoichem stuff problems

label Chemistry
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Aspirin (C9H8O4) is produced from salicylic acid (C7H6O3), and acetic anhydride (C4H6O3), as shown below.

C7H6O3 + C4H6O3 → C9H8O4 + HC2H3O2

(a) How much salicylic acid is required to produce 1.0  102 kg of aspirin, assuming that all of the salicylic acid is converted to aspirin?

(b) How much salicylic acid would be required if only 56% of the salicylic acid is converted to aspirin?

(c) What is the theoretical yield of aspirin if 181 kg of salicylic acid is allowed to react with 124 kg of acetic anhydride?

All

Jul 24th, 2015

for b: 2.05 x 102 Kg x 833.3= 174.2kg

for c: by calculation No# of mol we find that that acetic anhydrid is the limiting reactant so all calcutation depends on it 1 mol of acetic = 1 mol of aspirin ( from equation) mole of acitic = 125000g / 102 g/mol = 1225,50 mol = mol of aspirin mass of aspirin = 1.388x 180 = 220590g ( 250kg) and this is the theoretical yield

the pecentage yield = (actual / theoretical) x 100 % = (182 kg / 250kg) x 100 = 72.8%

Jul 24th, 2015

Jul 24th, 2015

moles aspirin = 1.0 x 10^2 x 1000 g / 180.157 g/mol= 555 moles salicylic acid = 555 mass salicilyc acid = 555 mol x 138.123 g/mol= 76658 g => 76.7 Kg

76.7 x 100 / 85 = 90.2 Kg

moles acid = 183000 g / 138.123 =1325 moles anhydride = 183000 g / 102.089 g/mol= 1793 ( in excess) we get 1325 moles aspirin mass = 1325 mol x 180.157 = 238708 g = >238.7 Kg

% = 187 x 100 / 238.7 = 78.3

Jul 24th, 2015

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Jul 24th, 2015
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Jul 24th, 2015
Sep 25th, 2017
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