Advertisements
Advertisements
प्रश्न
Give examples of exothermic reactions i.e. heat evolved in each of the following:
(a) reaction between a solid and a liquid
(b) reaction between two gases
Give two examples of exothermic reactions seen in everyday life.
Advertisements
उत्तर
(a) Reaction between a solid and a liquid:
CaO + H2O → Ca(OH)3 + Δ
(b) Reaction between two gases are:
\[\ce{N2 + 3H2 ⇌[Fe-450°][200 atoms.] 2NH3 + \triangle}\]
[finely divided iron (Fe) - catalyst]
Examples of exothermic reactions are:
- Rusting of iron – the reaction is slow and the heat evolved is very less, hence unnoticeable.
- Setting of cement – cement setting liberates heat, hence concrete structures are set slowly.
- Human Body – many chemical reactions in our body are exothermic & provide energy to survive.
APPEARS IN
संबंधित प्रश्न
Write the missing reactants and products and balance the equations.
NaOH + ............... `→` NaCI + ...................
Give a reason.
Wasp sting is treated with vinegar.
MULTIPLE CHOICE QUESTIONS
Tick the most appropriate answer
Which of the following is a reducing agent?
- oxygen
- chlorine
- hydrogen
- none of these
Fill in the blank:
The substances which undergo chemical change are called _______
Give an example of a reaction where the following are involved
Heat
State the original colour of the following substance and colour of residue obtained after heating.
Zinc carbonate
Give a chemical test to distinguish between the following gases.
HCl and Cl2
Give a chemical test to distinguish between the following gases.
NH3 and HCl
Give a chemical test to distinguish between the following gases.
SO2 and Cl2
What do you observe when dilute sulphuric acid is added to the following:
Sodium Sulphide
Complete the table given below.
| Addition of dil. H2SO4 to FeS | Odour of gas evolved |
Explain with the help of balanced equations, how precipitation reactions are used for identifying the positive radicals in three different salts, each having a different cation [positive ion].
Differentiate between the following:
Neutralization reaction and a precipitation reaction.
NPK are the primary nutrients for plants.
A reaction between an acid and a base is called ______.
State whether the following statement is true or false:
When a candle burns, both physical and chemical changes take place.
Beating an egg to make a cake is a ______.
Write a note on the catalyst.
Acid rain is a result of ______.
Write the effects of chemical reactions.
