Question

Describe your observations when potassium nitrate crystals are heated strongly in a test tube and a glowing splint is healed near the mouth of the test tube. Write a fully balanced chemical equation for the decomposition of potassium nitrate crystals.

Answer 1

When potassium nitrate crystals are heated vigorously in a test tube and a lighted splint is held near the test tube's mouth, the following observations are made:

1. Potassium nitrate's white crystals slowly melt into a colourless liquid.

2. The glowing splint catches fire, showing how molten potassium nitrate emits oxygen gas.

The given reaction is:

$\underset{\mathrm{Potassium}\mathrm{nitrate}\mathrm{Potassium}\mathrm{nitrite}\mathrm{Oxygen}}{2{\mathrm{KNO}}_3\stackrel{∆}{\to }2{\mathrm{KNO}}_2+{\mathrm{O}}_2}$

3. Potassium nitrate is decomposed by giving heat and produces ${\mathrm{KNO}}_2$ and ${\mathrm{O}}_2$.