Question

10 mL of gaseous hydrocarbon on combustion give
40 mL of CO2(g) and 50 mL of H,O (vap.). The
hydrocarbon is -
(1) CH
(2) CH10
(3) CH
(4)CH
8
10​

Answer 1

Answer:

first solution is -

10 mL of gaseous hydrocarbon on combustion gives 40 mL of CO2

The number of C atoms in the formula unit is 40/10×1=4

and

10 mL of gaseous hydrocarbon on combustion gives 50 mL of H2O

50/10×2 =10

The hydrocarbon is C4H10

 

Second solution is:-

the ratio of volumes is  

10 : 40 : 50  

1 : 4 : 5  

all the Carbon from the hydrocarbon is in the CO2  

10 ml of hydrocarbon produces 40 ml CO2,  

1 : 4 ratio  

So 1 mole hydrocarbon has 4 moles Carbon  

All the H ends up in the water  

10 ml hydrocarbon produces 50 ml water,  

1 : 5 ratio,  

but also each water has 2 H atoms  

So 1 mole hydrocarbon has 10 moles Hydrogen  

which gives  

C4H10  

You can balance an equation for combustion of C4H10 to check the answer  

C4H10 + 13/2 O2 --> 4CO2 + 5H2O

Explanation: