Give one example each of a chemical reaction involving a change of color, temperature and physical state respectively.

Open in App

Solution

Chemical reactions are characterized by the changes that are quite easily observed, these changes are:
Evolution of gases: In many chemical reactions one of the products is a gas.
For example: $\underset{(Z i n c g r a n u a l e s)}{\underset{⏟}{Z n (s)}} + \underset{(H y d r o c h l o r i c a c i d)}{\underset{⏟}{2 H C l (a q)}} \to \underset{(Z i n c c h l o r i d e)}{\underset{⏟}{Z n C l_{2} (a q)}} + \underset{(H y d r o g e n g a s)}{\underset{⏟}{H_{2} (g)}}$

2. Change in color: Certain chemicals have a certain color. Some of the chemical reactions are characterized by the change in color of the reactants.
For example: $\underset{(I r o n)}{\underset{⏟}{F e (s)}} + \underset{\underset{B l u e i n c o l o u r}{(C o p p e r s u l p h a t e)}}{\underset{⏟}{C u S O_{4} (a q)}} \to \underset{\underset{G r e e n i n c o l o u r}{(F e r r o u s s u l p h a t e)}}{\underset{⏟}{F e S O_{4} (a q)}} + \underset{(C o p p e r)}{\underset{⏟}{C u (s)}}$
Here $C u S O_{4}$ is blue in color and $F e S O_{4}$ is green, so a color change is observed once the reaction takes place.

3. Change in temperature: Some reactions are characterized by a change in temperature. Now this change can either be exothermic or endothermic.
Exothermic reactions are those when heat is getting evolved out of the system. An example would be: $\underset{(C a r b o n)}{\underset{⏟}{C (s)}} + \underset{(O x y g e n)}{\underset{⏟}{O_{2} (g)}} \to \underset{(C a r b o n d i o x i d e)}{\underset{⏟}{C O_{2} (g)}} + H e a t$
2. Endothermic reactions are those where heat energy is absorbed by the system. An example would be: $\underset{(N i t r o g e n g a s)}{\underset{⏟}{N_{2} (s)}} + \underset{(O x y g e n g a s)}{\underset{⏟}{O_{2} (s)}} \to \underset{(N i t r i c o x i d e)}{\underset{⏟}{2 N O (g)}} - H e a t$

4. Change of physical state: In many chemical reactions change of state is observed.
Example: $\underset{(A m m o n i a)}{\underset{⏟}{N H_{3} (g}}) + \underset{(H y d r o c h l o r i c a c i d)}{\underset{⏟}{H C l (g)}} \to \underset{(A m m o n i u m c h l o r i d e)}{\underset{⏟}{N H_{4} C l (s)}}$
Here Ammonia and hydrogen chloride is in a gaseous state combining to form Ammonium chloride in a solid state.

Suggest Corrections

Similar questions

Give an example of each of the following chemical changes.

(a) A reaction involving.

(i) Change of state.

(ii) Formation of the precipitate.

(b) An exothermic and an endothermic reaction involving carbon as one of the reactants.

Join BYJU'S Learning Program