Question

Some nickel(ii) sulfate solution was carefully placed
in the bottom of a beaker of water. The beaker was
then covered and left for several days.

a Describe what you would see after:
(i) a few hours
(ii) several days.
b Explain your answer to a using your ideas of the
kinetic theory of particles.
c What is the name of the physical process that
takes place in this experiment?

Answer 1

Solution:- (A) 7.8g

Decomposition of CaCO  

3

​

-

CaCO  

3

​

⟶CaO+CO  

2

​

 

At STP,

22.4L of a gas =1 mole

Therefore,

1.12L of CO  

2

​

=  

22.4

1

​

×1.12=0.05 mole

From the above reaction,  

1 mole of CO  

2

​

 is produced by 1 mole of CaCO  

3

​

.

0.05 mole of CO  

2

​

 will be produced by 0.05 mole of CaCO  

3

​

.

Therefore,

Molar mass CaCO  

3

​

=100g/mol

Mass of 0.05 mole of CaCO  

3

​

=0.05×100=5g

Now, again from the above reaction,

Molar mass of CaO=56g/mol

100g of CaCO  

3

​

 gives 56g of CaO.

5g of CaCO  

3

​

 will give  

100

56

​

×5=2.8g

Therefore,

Total mass residue =5+2.8=7.8g

Hence the mass of residue left is 7.8g.