Question

Analytical Chemistry Manual Experiment 6 27 EXPERIMENT 6 : SPECTROPHOTOMETRIC DETERMINATION OF IRON USING 1,10 - PHENANTHROLINE

Preparation of iron standard stock solutions:

Accurately (using an analytical balance ONLY) weigh 1.4 g of Fe(NH 4 ) 2 (SO 4 ) 2 · 6H 2 O, dissolve in 50 mL of 4% sulfuric acid in a beaker; transfer into a 1 L volumetric flask; adjust the volume and mix well. Note the purity of the Fe(NH 4 ) 2 (SO 4 ) 2 .6H 2 O - purity 0.998%. Transfer this solution into a 1 - L glass bottle.

Preparation of working iron standard solution:

Pipet 10.00 mL of the iron standard stock solution into a 500 - mL volumetric flask and dilute to the mark with water. Calculate the molarity of Fe in the solution from the weight of Fe(NH 4 ) 2 (SO 4 ) 2 .6H 2 O used and its purity (0.998%). Transfer this solution into a 1 L glass bottle. This solution is called the working iron standard solution. The following procedure is given for one trial. You have to run three trial

** confused for purity calculation of fe

Answer 1

QUESTION: Calculate the molarity of Fe in the solution from the weight of Fe(NH 4 ) 2 (SO 4 ) 2 .6H 2 O used and its purity (0.998%).

The mass of Fe in the sample of 1.4 grams is as follows. Using purity,

The no. of moles of Fe in the sample can be calculated using the atomic mass as follows. (atomic mass= 55.845g/mol)

The concentration of the stock solution is as follows.

We pipet 10.00ml from the iron stock solution and dilute it to 500.00ml. We use the given relationship to calculate the new concentration of iron.