Q.

Butane reacts with oxygen to produce carbon dioxide and water following the equation given below

C4H10(g)+132O2(g)  4CO2(g)+5H2O(l)

If 174.0 kg of butane is mixed with 320.0 kg of O2, the volume of water formed in litres is _____. (Nearest integer)

[Given: (a) Molar mass of C, H, O are 12, 1, 16 g mol-1 respectively, (b) Density of water = 1 g mL-1]                      [2025]


Ans.

(138)

Molar mass of butane (C4H10)=(4×12+10×1)g/mol=58g/mol

Moles of butane (nC4H10)=Mass of butaneMolar mass of butane=17400058 g mol-1=3×103mol

Moles of oxygen (nO2)=Mass of oxygenMolar mass of oxygen=320000 g32 g mol-1=10×103mol

C4H10+6.5O2  4CO2+5H2O

As per reaction stoichiometry, to react with 3×103 mol of butane, 6.5×3×103mol i.e 19.5×103 mol oxygen is needed. But available oxygen is 10×103 mol.  
Thus, oxygen is the limiting reagent. Amount of water produced depends upon amount of limiting reagent, i.e. oxygen.  

As per reaction stoichiometry:

nH2O5=nO26.5

nH2O5=10×1036.5

nH2O=5×10×1036.5=7692.3mol

Mass of water (WH2O)=nH2O×MH2O=7692.3×18 g=138461.4g

Density of water (dH2O)=1g/mL

Volume of water =WH2OdH2O=138461.4g1g mL-1=138461.4mL=138.46L138L