Question

Why magnesium ribbon is chosen and not magnesium rod in burning experiments?

Answer 1

Magnesium burns in Nitrogen gas forming Magnesium Nitride $\left(M{g}_3{N}_2\right)$. It takes place only at high temperature of 800 °C. $M{g}_3{N}_2$ is a green-yellow powder.

A ribbon of thickness less than 0.1 mm is used for laboratory experiments. A rod is not used.

1. It is easier to heat the ribbon to 800°C with a simple splinter. Large/thick rod takes a long time or may not burn with a splinter in $N_2.$

2. Large surface area ensures complete exposure to $N_2$ Nags and complete burning of Mg.

3. The powder (greenish yellow) formed will cover the surface of the rod and so the experiment is not properly performed.

4. Magnesium once starts burning, it doesn't stop easily. So ribbon (very having small mass) is used.

5. Magnesium rods are used as electrodes in batteries and electrolysis experiments. Also to dissolve Mg in an acid or solution.

Mg ribbons are used in experiments related to burning.