posted by jackson .
aspirin is synthesized through the following reaction
a)Assuming the maximum yield that could be obtained is 76.8% what mass of Aspirin C9H8O4 could be obtained from this reaction when 2.00 * 10^2 grams of C7H6O3 reacts with 145.30 grams of C4H6O3.
b)calculate the mass of excess reagent that is left over in this reaction?
Let's call these r1 and r2 for reagent 1 and reagent 2. So r1 is C7H6O3 and r2 is C4H6O3. You made a typo in the equation. You typed an = sign for a + sign.
a. Which reactant is limiting?
mols r1 = grams/molar mass = estimated 1.45
mols r2 = g/molar mass = approx 1.42
This is a 1:1 reaction ratio; therefore, the smaller number is the limiting reagent and the other is the excess reagent. Limiting reagent is r2.
Therefore, 1.42 mols product will be formed. Convert to grams. g = mols x molar mass product. Multiply by percent yield (0.768) to obtain the actual yield.
b. r2 is the limiting reagent. r1 is the excess. How much of the excess reagent is used. That is mols r2 x (1 mol r1/1 mol r2) = 1.42 x (1/1) = 1.42 used. You had 1.45 initially. The difference is what was not reacted. That x molar mass = grams.