The heat evolved in the combustion of methane is given by the equation `:`
`CH_(4)(s) + 2O_(2)(g) rarr CO_(2)(g) + 2H_(2)O(l), DeltaH = - 890 .3 kJ mol^(-1)`
(a ) How manygrams of methane would be required to produce 445.15 kJ of heat of combustion ?
(b ) How many grams of carbon dioxide would beformed when 445.15 kJ of heat is evolved ?
(c ) What volume of oxygen at STP would be used in the combustion process (a ) or (b) ?

Explanation

(a) From the given equation ,
890.3 kJ of heat is produced from 1 mole of`CH_(4), i.e., 12+4 = 16 g ` of `CH_(4)`
(b ) `:. 445.15kJ` of heat is produced from 8g of `CH_(4)`
(b) From the given equation, when 890.3 kJ of heat is evolved , `CO_(2)` formed `=1` mole `=44 g `
`:. `When 445.15 kJ of heat is evolved , `CO_(2)` formed `= 22g`
(c ) From the equation , `O_(2)` used in the production of 890.3 kJ of heat `=2` moles `= 2 xx 22.4 ` litres at STP
`= 44.8` litres at STP
Hene, `O_(2)` used in the production of 445.1 5 kJ of heat = 2 22.4 litres at STP.