Why are fireworks colourful?

Photo by Carson Arias on Unsplash

Fireworks (crackers) are used on various occasions of national, religious and social festivals in almost all the countries of the world. It is estimated that every year a sum of Rs. 5000 crores is spent all over the world on fireworks of about 300 varieties. When they are ignited, they explode and present a riot of colours. Fireworks are prepared by a mixture of potassium nitrate, sulphur, coal and salts of certain metals. The colour is provided by salts of metals like strontium, barium, magnesium and sodium. They are mixed with potassium chlorate. Barium salts give out green colour, while strontium sulphate produces light sky blue colour. Strontium carbonate produces yellow colour whereas strontium nitrate produces red, salts of sodium impart yellow colour, those of copper impart blue colour. Aluminium powder in the fireworks produces the silvery rain. When fireworks explode these salts burn in fireworks, various colours come out and present a spectacular sight. The colours to fireworks are provided by salts of different metals China was the first country to manufacture fireworks. Hundreds of years later, Europe, Arabia and Greece also manufactured them. Some time ago, in a celebration in Japan, colourful fireworks were lighted that went up to a height of 915 metres and were scattered in a radius of 305 metres.