Question

(a) A student took 2-3g of a substance x in a glass beaker.He observed bubbles along with hissing noise. The beaker becomes quite hot . Identify x. What type of reaction it is

Answer 1

A student took 2-3 g of a substance x in a glass beaker.

X can be anything, an acid or base at present we have no hint about that.

Now, let's read the question;

“A student took 2-3g of a substance x in a glass beaker. He observed bubbles along with hissing noise. The beaker becomes quite hot.”

→ Beaker is quite hot. Means, the reaction is Exothermic reaction.

Also, the student observed bubbles along with hissing noise.

The substance X is Calcium Oxide (Another name - Quick lime).

Used in white washing.

If Calcium oxide (CaO) reacts with water (vigorously) to produce Calcium Hydroxide [Ca(OH)2] and heat.

CaO (s) + H2O (l) → Ca(OH)2 (aq) + heat

Another name of Calcium Hydroxide is Slaked lime.

The above reaction is Combination Reaction too, as two or more reactants combine to form a single product.

Answer 2

QuestioN :

student took 2 3g of substance X in a glass beaker and poured water over it slowly.he observed bubbles along with hissing noise.the beaker become quit hot.identify X. What type of reaction is it is.

GiveN :

• Student observed bubbles with hissing noise when water is added.
• Beaker becomes hot

SolutioN :

A student took 2-3 g of a substance in a glass beaker.

If the beaker becomes hot after addition of water. So, we can say that the Reaction is Exothermic in nature.

And student also notice bubbles with hissing noise on adding of Water. So, we come to know that the given substance is Calcium Oxide (CaO).

It is also known as Quick Lime

Now, the reaction involved is :

$\sf{CaO \: + \: H_2O \: \to \: Ca(OH)_2 \: + \: Heat}$

• Therefore the Above Reaction is Combination Reaction.