1. Calculation of the percentage yield. First report the weights recorded for the recrystallisation part in the table below:

	Mass of item (g, 2 d.p.)
(1) Empty watch glass	38.30 g
(2) Watch glass + wet crystals	41.75 g
(3) Watch glass + dry crystals	41.48 g
(4) Yield = (3) - (1)	3.18 g

(d.p. = decimal places)

1. Showing your working, calculate the number of moles of 4-aminophenol, and the number of moles ethanoic anhydride used in the experiment (quote 3 significant figures).

5.5g of 4-aminophenol used:

Molecular mass of 4-aminophenol: 109.1

Moles = mass/molecular mass

Moles = 5.5/109.1 = 0.05041247 = 0.0504

Number of moles of 4-aminophenol used in the experiment = 0.0504 mol

6.cm^3 / 6.48g of ethanoic anhydride used:

Molecular mass of ethanoic anhydride: 102.1

Moles = mass/molecular mass

Moles = 6.48/102.1 = 0.06346719 = 0.0635

Number of moles of ethanoic anhydride used in the experiment = 0.0635 mol

(2 x 2 marks)

2. State the stoichiometric amounts of the reaction and deduce which of the two reagents is the limiting factor in the reaction. From this determine the maximum mass obtainable for the product this is the theoretical yield (quote 3 significant figures).

question 1) ii) is the only question i was stuck with, thanks