Question

During performing an experiment on neutralisation reaction, Ravi took

about 100 mL of sodium hydroxide solution and pour approximately the same

amount of concentrated hydrochloric acid to it.

He observed a very vigorous reaction with evolution of large amount of heat.

When he dipped litmus paper into the solution it turned red. He was surprised

with the result though he had read all the instructions and precautions given to

him by his teacher.

(a) What was the expected result of the experiment?

(b) What went wrong in the experiment performed by Ravi?

(c) Why Ravi observed a very vigorous reaction with evolution of large amount

of heat when he added concentrated hydrochloric acid to sodium hydroxide?​

Answer 1

Answer:

1. The expected result was no change in the litmus paper as Sodium Salt (neutral) was supposed to form along with Water.
2. Ravi took concentrated acid which has very acidic in nature.
3. As he took concentrated acid instead of diluted acid

Explanation:

Hope It Helps You..

Jay.. ^_^

Answer 2

The answers are as follows-

(a) The expected result of the experiment was- no change in the colour of litmus paper.

• To perform a neutralisation reaction, the aqueous solution of acid and base are added in equal amounts that result in the formation of salt and water. The heat is released in this process.
• As salt is neutral in nature, if we test the pH of the solution after the experiment, it will show no colour change.

(b) The thing that went wrong in the experiment performed by Ravi is- he used concentrated hydrochloric acid instead of dilute hydrochloric acid.

• The concentrated hydrochloric acid is highly acidic as it contains many hydronium ions. Thus, when he used concentrated hydrochloric acid to react with sodium hydroxide, it made the solution acidic due to the production of a large number of hydronium ions. Thus, when Ravi dipped the pH paper in the solution, it turned red.

(c) Ravi observed a very vigorous reaction with the evolution of large amount of heat when he added concentrated hydrochloric acid to sodium hydroxide because the reaction is exothermic.

• The reaction of an acid with a base is usually an exothermic reaction in which a large amount of heat is released.