Q36 of 59 Page 32

What do you understand by exothermic reaction and endothermic reaction? Give one example of each type.

Exothermic reaction- The reaction in which heat is evolved is called exothermic reaction.


for example,


CaO + CO2→ CaCO3 ΔH=-178kJmol-1


Endothermic reaction- The reaction in which heat is absorbed is called endothermic reaction.


for example,


2NH3 → 3N2+ H2 ΔH=918kJmol-1


More from this chapter

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34

p-Block elements form acidic, basic and amphoteric oxides. Explain each property by giving two examples and also write the reactions of these oxides with water.

 35

How would you explain the fact that first ionisation enthalpy of sodium is lower than that of magnesium but its second ionisation enthalpy is higher than that of magnesium?

 37

Arrange the elements N, P, O and S in the order of-

(i) increasing first ionisation enthalpy.


(ii) increasing non-metallic character.


Give reason for the arrangement assigned.


 38

Explain the deviation in ionisation enthalpy of some elements from the general trend by using Fig. 3.2.