Question

In the following reaction 2C6H6 + 15O2 12CO2 + 6H2O how many grams of oxygen will react with 10.47 grams of benzene (C6H6)?

Answer 1

$2 C_{6}H_{6} + 15O_{2} ----->\ \textgreater \ 12CO_{2} + 6H_{2}O$

$mol of benzene = \frac{mass}{Mr}$
                                = $\frac{10.47g}{(6 * 12) (6 * 1) g/mol}$
                                = 0.134 mol

mol of oxygen: 
                 ratio of $C_{6} H_{6} : O_{2}$
                 =  2 : 15
                 =  1 : 7.5

: . mol of $O_{2}$ = 0.134mol * 7.5
                                         = 1.01 mol

Mass of Oxygen = mol * Mr
                           = 1.01 mol * (16*2) g/mol
                           = 32.22g 

Note: Mr is molar mass