Question

You will be carrying out reactions all semester in lab and will need to be able to calculate theoretical and % yields. In preparation for this work, I would like you to practice using the reaction below. 1. Determine which reagent (A or B) is the limiting reagent. 2. Determine the actual % Yield of the product C. Use the following amounts of starting material and product to complete the necessary calculations. (A, 20mL; B, 10mL; C, 10 g).

A + B --H₂o at 25*c--> C

A: Acetic Anhydride, B: Aniline, C: Acetanilide

Answer 1

first of all let me tell you that usually we take ml=g

so the reaction would be like this:

20 g of A is available to react with 10 g of B.

molar mass of A= 102.1 g

moles of A= 20/102.1 = 0.196 moles

molar mass of B= 93.13 g

moles of B= 10/93.13 = 0.107 moles

according to the stochiometric coefficients of the reactant, we see that one mole of A reacts with one mole of B to form one mole of C.

Here, B is present in smaller amount, i.e lesser number of moles, so it is the limiting reagent.

b)

So, 0.107 moles of A react with 0.107 mole of B to form 0.107 moles of C.

molar mss of C= 135.17 g

mass obtained= 0.107*135.17= 14.46 g this is the actual yield.