Exercise 11. Crystallized Barium Hydroxide

Prepare a hot solution of 100 g. of commercial barium chloride in 200 cc. of water in an Erlenmeyer flask. Add a solution of 30 g. of sodium hydroxide in 30 cc. of water and set the flask aside for crystallization. When cold, decant off the mother liquor as completely as possible and dissolve the crystals in as little hot water as will suffice. The solution will be turbid from suspended barium carbonate and must be filtered into a vessel containing purified air. Proceed as follows Secure an Erlenmeyer flask of about 500 cc. capacity and fit it with a two-hole stopper, carrying a right-angled tube that reaches to near the bottom of the flask (Fig. 3). Through the other hole insert a short right-angled tube 

Obtain two funnels the rims of which are of just the same size. Provide one of them with a stopper which fits your filter flask and also with a Witte plate. Attach the calcium chloride drying tube to the stem of the other. / a Provide also a piece of rubber tape such as / is used to wrap joints in electrical wires and 

F 4 long enough to reach around the rim of the funnels and lap over for a joint. 

Shake the flask containing the crystals until any cake that may have formed is broken up and quickly pour the contents of the flask onto the Witte plate. Place the second funnel rim to rim with the first as a cover and bind the rubber tape around the joint to hold the two together by an airtight joint. Pump off the mother liquor and continue to pump air through the flask until 

Topics Law of mass action solubility product Mellor, I, 300, 494, 996 textbooks on physical chemistry. 

---