Molecular intyerpreation: How many `O_(2)` molecules react with `74 CH_(4)` molecules according to the preccdign equation?
Strategy: The balanced equation tells us that one `CH_(4)` molecule always reacts with two `O_(2)` molecules. Either we go for unitary method or construct a unit factor from the above fact:
`(2 O_(2) "molecules")/(1 CH_(4) "molecule")`

Explanation

`? O_(2)` molecules `= 74 CH_(4)` molecules `xx (2 O_(2) "molecules")/(1 CH_(4) "molecule")`
`= 148 O_(2)` molecules