Chemistry Reference
In-Depth Information
Material: Evaporating dish (Pyrex glass), watch glass, funnel, iron and carbon
electrodes, burner, direct current voltage source (10 V, 10 A), tripod with wire
gauze; lithium chloride (Xn), potassium chloride.
Procedure: A mixture of 21 g of anhydrous lithium chloride and 7 g of potassium
chloride is to be prepared, put in the evaporating dish and - as the figure shows -
connected to the electrodes. Set a direct current voltage of 8 V. The mixture is to be
melted and electrolyzed on the tripod with wire gauze (under the hood; roaring
flame). The electrolysis is to be interrupted after about 10 min to extract the solidi-
fied lithium (a layer of chloride protects the metal). The sample can be analyzed after
cooling. Especially, the reaction with water and the thereby emerging hydrogen
can be demonstrated. Please note: In case of igniting lithium, do not try to extinguish
it with water!!! Use sand or sodium chloride!
-
8v
Iron
electrode
Glass funnel
Graphite
electrode
Sodium
hydroxide solution
Platinum
electrodes
10
-
+
Observation: Lithium deposits at the cathode, chlorine gas forms at the anode.
Lithium reacts with water, as known. The emerging hydrogen burns with a red flame.
