Question

Take a long magnesium ribbon. Clean it well by scraping it with a knife. Cut the magnesium ribbon into small pieces which are less than half a centimeter long. Put one piece of this magnesium ribbon carefully into 5 mL dilute hydrochloric acid taken in a test tube. Write the observation.

Experiment-2

Take 1 mL of acid in the test tube.Put the pieces of magnesium one by one into this.What may be the reason?

Answer 1

Magnesium reacts with hydrochloric acid according to the equation: Mg(s) + 2 HCl(aq) --> MgCl ₂(aq) + H₂(g)

experiment 1 says
1 Mg piece added to 5ml of HCl
experiment 2 says
many Mg peices added to 1ml HCl

the rate of experiment 1 willbe faster as the acid taken is more quantitatively.
the rate of the reaction depends on the number of collision taking place between the molecules.
more number of collisions takes place with more number of molecules . Increase in HCl concentration allows more chance for Mg to react.
you can see the hydrogen evolving in experiment 1 willbe more vigorous(bubbles) than in experiment 2