You will be carrying out reactions all semester in lab and will need to be able

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

Explanation / Answer

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.

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