Question

The burning of a piece of magnesium ribbon in air is a chemical change. Explain.

Answer 1

Hint: Chemical changes are referred to a phenomenon when a substance combines with another substance which leads to formation of a new substance this is called as chemical synthesis, chemical decomposition that is when a substance breaks up into two or more substances is also referred as a chemical change. These processes are called chemical reactions and, in general, are irreversible in nature.

Complete step by step answer:
When we learn about chemical reactions they are divided into two subclasses exothermic reactions and the other is endothermic reactions, in exothermic reactions there is a release of heat when the reaction takes place whereas in the endothermic reactions there is a consumption of heat when the reactions takes place. Magnesium ribbon is a kind of elemental form of carbon and when this is burned in the presence of oxygen which is present in the air also known as combustion, it gives rise to the formation of a chemical compound known as magnesium oxide \[MgO\], and the magnesium ribbon turns into a powder due to a formation or in other words breakdown of magnesium ribbon thus, this infers it is a chemical reaction. The reaction is shown as follows:
\[2Mg + {O_2} \to 2MgO\]

Note:
Magnesium ribbon when burned produces a white flame, and the ribbon is obtained generally from magnesite and in bodies of salt water and has a major use in polytechnic and formation of alloys and also in flash photography as well.