Question

The reactions of Group 1 metals with water
Some students have summarized the reactions of the alkali metals with water below and it is your job to mark their work and explain if they have made any mistakes.


Lithium
Lithium floats on water because it is lighter than water. It moves around on the surface and forms a ball as it starts to dissolve. There is lots of fizzing as hydrogen gas is produced. The gas does not light and the solution produced at the end of the reaction turns universal indicator yellow because it is a weak acid.

word equation:
lithium + water → lithium acid + hydrogen


Sodium
Sodium is less reactive than lithium. It floats on the surface because it is less dense than water. As it reacts the metal melts forming a ball. Lots of bubbles show a gas is produced and this gas is oxygen. Sometimes a lilac flame is produced. The solution that forms is an alkali with a pH of 14 (purple with universal indicator). The ion that makes the solution an alkali is Na+.

word equation:
sodium + water → sodium hydroxide + oxygen



Potassium
Potassium is the least reactive of the three metals tested showing that the reactivity of the alkali metals decreases down the group. Potassium does not melt because it has a lower melting point than sodium and lithium. There is a fizzing noise as hydrogen gas is produced. The hydrogen ignites to produce a lilac flame. The colour of the flame is due to potassium atoms in the flame. Potassium hydrogen oxide is produced.

word equation:
potassium + water → potassium hydrogen oxide + hydrogen

Answer 1

Respuesta:

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