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Combustible vapor-air mixtures are flammable over a
Chapter 6, Problem 100P(choose chapter or problem)
Combustible vapor-air mixtures are flammable over a limited range of concentrations. The minimum volume % of vapor that gives a combustible mixture is called the lower flammable limit (LFL). Generally, the LFL is about half the stoichiometric mixture, the concentration required for complete combustion of the vapor in air. (a) If oxygen is 20.9 vol % of air, estimate the LFL for n-hexane, C6H14. (b) What volume (in mL) of n-hexane (d =0.660 g/cm3) is required to produce a flammable mixture of hexane in 1.000m3of air at STP?
Questions & Answers
QUESTION: Problem 100P
Combustible vapor-air mixtures are flammable over a limited range of concentrations. The minimum volume % of vapor that gives a combustible mixture is called the lower flammable limit (LFL). Generally, the LFL is about half the stoichiometric mixture, the concentration required for complete combustion of the vapor in air. (a) If oxygen is 20.9 vol % of air, estimate the LFL for n-hexane, C6H14. (b) What volume (in mL) of n-hexane (d =0.660 g/cm3) is required to produce a flammable mixture of hexane in 1.000m3of air at STP?
ANSWER:
Solution 100P:
Step 1: (A)
The combustion reaction of hexane is given below:
As we know, at constant temperature and volume, the moles of gases are directly proportional to their volumes.
Thus, 2.0 L hexane = 19 L of O2 (g)
Therefore,
The volume of required = 1.0 L air
= 0.022 L )