Chemistry
A small piece of calcium metal is put into a small trough containing water. There is effervescence and white turbidity is formed.
(a) Name the gas formed in the reaction. How would you test the gas?
(b) Write an equation for the reaction.
(c) What do you observe when a few drops of red litmus solution are added to the turbid solution?
Hydrogen
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Answer
(a) Hydrogen gas.
It burns silently in air or oxygen with a pale blue flame, forming water.
2H2 + O2 ⟶ 2H2O
When it is premixed with air or oxygen, it explodes with a pop sound.
(b) Ca + 2H2O ⟶ Ca(OH)2 + H2 ↑
(c) The solution turns blue.
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