Chemistry Reference
In-Depth Information
Procedure: The test tube is to be filled with a spoonful of wet sand and fixed
horizontally. The magnesia groove filled with magnesium turnings is to be put
into the middle of the test tube. Then the test tube is to be closed with stopper and
outflow pipe (see figure). The metal is to be heated strongly. By warming the sand,
water vapor reacts strongly with magnesium, the produced gas is to be collected in a
cylinder, the gas is ignited later. After the reaction the stopper is to be removed, to
prevent water from running into the test tube.
A few calcium turnings are to be mixed with water. During the reaction, a second
test tube is to be put over the test tube with the opening downwards, this opening is
to be put close to a flame. Caution: little bang. The milky suspension in the first test
tube is to be tested with indicator paper.
Observation: When heated, magnesium reacts with a very bright light. A rapid gas
formation starts, the cylinder fills up with gas. The gas combusts with a whistling
noise: hydrogen.
At room temperature calcium reacts to an alkaline solution: calcium hydroxide
solution (“lime water”). Solid white calcium hydroxide forms a milky suspension.
The observed gas mixture combusts with the familiar whistling noise: hydrogen.
E5.20: Student Experiments on the Lithium-Water Reaction
Student work sheet: “The reaction of lithium with water”
Problem: How can we explain the reaction of alkaline metals with water?
Working material per group: beaker, glass dish, small glass cylinder with cover
glass, tweezers; 3 pea-size pieces of lithium (C/F), universal indicator paper,
phenolphthalein solution (0.1% in ethanol) (F), matches. Safety goggles must be
worn!
