Question

Liquid hexane, C6H14, burns in oxygen gas to yield carbon dioxide and water. What is the minimum mass of oxygen required for the complete reaction of 20.0 mL of hexane?Given density of hexane=0.660 g/mL and MW=86.8 g/mL2 C2H14+19O2------> 12CO2+14 H2OPossible answers4.9g7.42g46.6g70.6g93.2g

Answer 1

Answer: 46.6 grams

Explanation:

$2C_6H_{14}+19O_2\rightarrow 12CO_2+14H_2O$

Given : density of hexane = 0.660 g/ml

volume of hexane = 20 ml

Mass of hexane = ${\text {density of hexane}}\times {\text {volume of hexane}}=0.660g/ml\times 20ml=13.2g$

moles of hexane =$\frac{\text {given mass}}\times {\text {molar mass}}=\frac{13.2g}{86.18g/mol}=0.15moles$

According to stoichiometry :

2 moles of hexane reacts with 19 moles of oxygen

Thus 0.14 moles hexane will react with =$\frac{19}{2}\times 0.15=1.45$ moles of oxygen

Mass of oxygen =$moles\times {\text {molar mass}}=1.45\times 32=46.6g$

Thus minimum mass of oxygen required for the complete reaction of 20.0 mL of hexane is 46.6 grams.