Xylene (ZIGH-leen) is an important organic molecule isolated from petroleum oil.
ID: 1048113 • Letter: X
Question
Xylene (ZIGH-leen) is an important organic molecule isolated from petroleum oil. It is often used as a thinner for oil-based paints. a. Elemental analysis of a sample of xylene shows that the mass percent of carbon is 90.51% and the mass percent of hydrogen is 9.49%. What is the empirical formula of xylene? b. The molar mass of xylene is 106.17 g/mol. What is the molecular formula of xylene? c. In the laboratory setting, xylene burns in limited oxygen environments to produce carbon monoxide and water vapor. Write the balanced reaction for this reaction. d. If 12.5 g of xylene were combusted using the equation from part c, how many grams of oxygen gas would be required to react completely with the xylene? e. A vessel containing 45.8 mL of xylene (density = 0.8787 g/mL) and 31.0 g of O_2 produced carbon monoxide and water. Which reagent is the limiting reagent in this reaction? How many grams carbon mi tide are produced in the reaction? f. It 1.40 g of CO were actually isolated from the reaction in part e, what would be the percentage yield of the reaction?Explanation / Answer
103. Xylene
a. moles of C = 90.51/12 = 7.54 mols
moles of H = 9.49/1 = 9.49 mols
divide by smallest number
C = 7.45/7.45 = 1
H = 9.45/7.45 = 1.3
Multiply with 4,
Empirical formula = C4H5
c. ratio (moar mass/empirical formula mass) = 106.17/53 = 2
So,
molecular formula of xylene = C8H10
d. Combustion of xylene with O2
2C8H10 + 13O2 ---> 16CO + 10H2O
e. moles of xylene = 45.8 x 0.8787/106.17 = 0.38 mols
moles of O2 = 31/32 = 0.970 mols
Is all of xylene is consumed we would get = 0.38 x 16 x 28/2 = 85.12 g of CO
If all of O2 is consumed we would get = 0.970 x 16 x 28/13 = 33.43 g CO
As mass of CO produced is lower starting with O2, this is the limiting reagent.
f. Actual yield of CO = 1.40 g
Percent yield of reaction = 1.40 x 100/33.43 = 4.20%
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