Show the calculation of (1) the expected grams of salicylic acid (C7H6O3) formed in the reaction of 1.75 grams of methyl salicylate (C8H8O3) with excess NaOH and then show the calculation of (2) the % yield if the actual yield of salicylic acid is 1.19 grams.
Show the calculation of (1) the expected grams of aspirin (C9H8O4) formed in the reaction of 2.7 grams of salicylic acid (C7H6O3) with excess acetic anhydride and then show the calculation of (2) the % yield if the actual yield of aspirin is 1.44 grams.
To calculate the expected grams of salicylic acid formed, we need to find the moles of methyl salicylate (C8H8O3) and then use the balanced chemical equation to determine the moles of salicylic acid (C7H6O3) produced.
Step 1: Calculate the moles of methyl salicylate (C8H8O3).
Given mass of methyl salicylate = 1.75 grams
Molar mass of methyl salicylate (C8H8O3) = (12.01 x 8) + (1.01 x 8) + (16 x 3) = 152.15 g/mol
Moles of methyl salicylate = mass / molar mass
Moles of methyl salicylate = 1.75 g / 152.15 g/mol
Step 2: Use the balanced chemical equation to determine the moles of salicylic acid (C7H6O3) produced.
The balanced equation for the reaction is:
C8H8O3 + NaOH → C7H6O3 + NaC8H7O3
From the equation, we see that 1 mole of methyl salicylate (C8H8O3) reacts to produce 1 mole of salicylic acid (C7H6O3).
Moles of salicylic acid = moles of methyl salicylate
Step 3: Calculate the mass of salicylic acid (C7H6O3) formed.
Given moles of salicylic acid (C7H6O3) = moles of methyl salicylate
Molar mass of salicylic acid (C7H6O3) = (12.01 x 7) + (1.01 x 6) + (16 x 3) = 138.12 g/mol
Mass of salicylic acid = moles of salicylic acid x molar mass of salicylic acid
Mass of salicylic acid = moles of methyl salicylate x molar mass of salicylic acid
Mass of salicylic acid = (1.75 g / 152.15 g/mol) x 138.12 g/mol
Now, let's move on to calculate the percentage yield.
Step 1: Calculate the percentage yield.
Given actual yield of salicylic acid = 1.19 grams
Percentage yield = (actual yield / theoretical yield) x 100
Theoretical yield is the mass of salicylic acid calculated in the previous step.
Percentage yield = (1.19 g / [moles of methyl salicylate x molar mass of salicylic acid]) x 100
Using the values calculated earlier, you can substitute them into the equation to find the percentage yield.