Question

Calculate the % yield of the rection between 6.00 grams of salicylic acid and excess acetic anhydride to form 3.12 grams od Aspirin:

Answer 1

To calculate the percent yield of the reaction, you need to compare the actual yield to the theoretical yield. The theoretical yield is calculated based on the balanced chemical equation and assumes that the reaction goes to completion without any side reactions or losses. The percent yield is calculated by dividing the actual yield by the theoretical yield and multiplying by 100.

Step-by-step explanation:

To calculate the percent yield of a reaction, you need to compare the actual yield to the theoretical yield. The theoretical yield is calculated based on the balanced chemical equation and assumes that the reaction goes to completion without any side reactions or losses. In this case, the balanced chemical equation for the reaction is:

salicylic acid + acetic anhydride → aspirin + acetic acid

To calculate the theoretical yield of aspirin, you need to determine the limiting reactant. Based on the given values, it appears that the limiting reactant is salicylic acid. So, we will use the mass of salicylic acid to calculate the theoretical yield of aspirin. The molar mass of salicylic acid is 138.12 g/mol. Now we can calculate the theoretical yield:

Convert the mass of salicylic acid to moles: 6.00 g salicylic acid * (1 mol salicylic acid / 138.12 g salicylic acid) = 0.04339 mol salicylic acid

Use the balanced chemical equation to determine the molar ratio between salicylic acid and aspirin: 1 mol salicylic acid / 1 mol aspirin

Convert the moles of salicylic acid to moles of aspirin by multiplying by the molar ratio: 0.04339 mol salicylic acid * (1 mol aspirin / 1 mol salicylic acid) = 0.04339 mol aspirin

Convert the moles of aspirin to grams by multiplying by the molar mass of aspirin: 0.04339 mol aspirin * (180.16 g aspirin / 1 mol aspirin) = 7.81 g aspirin

The theoretical yield of aspirin is 7.81 grams. Now, to calculate the percent yield, divide the actual yield by the theoretical yield and multiply by 100:

% yield = (actual yield / theoretical yield) * 100

Plugging in the given values:

% yield = (3.12 g / 7.81 g) * 100 = 39.97%

Answer 2

You identify the limiting reactant by calculating the moles of product that can be formed from each reactant.

Explanation: Then you calculate the theoretical yield of product from the amount of the limiting reactant.

EXAMPLE Aspirin is prepared by the reaction between acetic anhydride and salicylic acid.

acetic anhydride + salicylic acid → aspirin + acetic acid

C 4 H 6 O 3 + C 7 H 7 O 3 → C 9 H 8 O 4 + C 2 H 4 O 2 m m A m l + m B m m → m l l C m l l + m l D

What is the theoretical yield of aspirin ( C ) if you reacted 4.32 g of acetic anhydride ( A ) with 2.00 g of salicylic acid ( B )?

Solution :

The molar masses are

Acetic anhydride = A = C 4 H 6 O 3 = 102.1 g/mol

Salicylic acid = B = C 7 H 6 O 3 = 138.1 g/mol

Aspirin = C = C 9 H 8 O 4 = 180.2 g/mol

Identify the limiting reactant We calculate the moles of each reactant and then use the molar ratios from the balanced equation to calculate the moles of aspirin.

Moles of aspirin from A = 4.32 g A × 1 mol A 102.1 g A × 1 mol C 1 mol A = 0.0423 mol C

Moles of aspirin from B = 2.00 g B × 1 mol B 138.1 g B × 1 mol C 1 mol B = 0.0145 mol C B gives the smaller amount of aspirin, so B is the limiting reactant.

Calculate the theoretical yield 0.0145 mol C × 180.2 g C 1 mol C = 2.61 g C