Calculating percentage yield

IGCSE Chemistry                                               Calculating percentage yield            

Aim

To compare the theoretical yield of one of the products of a precipitation reaction to the actual yield of the same product determined by experiment.

Equipment

·         balance, ± 0.01g ·         graduated cylinder, 100 cm3 ·         2 beakers, 250 cm3 ·         1 beaker, 100 cm3

·         clamp and stand ·         funnel ·         stirring rod

Materials

·         lead (II) nitrate, Pb(NO₃ )₂ 

·         potassium iodide, KI

·         filter paper

 

Procedure

1.         Using the balance, measure out approximately 3.30 g of lead (II) nitrate.

2.         Place the lead (II) nitrate in a clean 250 cm³ beaker and add 50 ml of water. Stir thoroughly ensuring that all crystals are dissolved. Rinse the stirring rod.

3.         Measure out more than 4.00 g of potassium iodide and place it in a clean 100 cm³ beaker and add 50 cm³ of water. Stir until all crystals are dissolved.

4.         Pour the potassium iodide solution into the 250 cm³ beaker containing the lead (II) nitrate solution. Stir.

5.         Fold a piece of filter paper and place it in a funnel.

6.         Pour slowly the mixture from the 250 cm³ beaker into the funnel.

7.         Rinse the beaker with about 20 cm³ of water and pour the rinse water through the filter.

8.         Repeat step 7 until all the precipitate (lead iodide) is out of the beaker.

9.         Wash the precipitate by pouring about 10 cm³ of distilled water through the filter.

10.       Remove the filter paper and precipitate from the funnel and place it somewhere in the lab out of the way and allow it to dry.

Precaution   

Lead compounds are poisonous! Wash your hands after you have finished the practical work.