J.R. S. answered • 05/29/18
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Ph.D. in Biochemistry--University Professor--Chemistry Tutor
From the balanced equation C3H8 + 5O2 ==> 3CO2 + 4H2O you see that 1 mole of C3H8 (propane) requires 5 moles O2 gas. 12.0 g C3H8 x 1 mole/44 g = 0.273 moles propane
0.273 moles propane x 5 moles O2/mole propane = 1.36 moles O2 needed.
Now, the actual VOLUME of O2 needed will depend on the temperature and pressure of the system. If we assume STP (standard temperature and pressure; 1 atm 273K), then 1 mole O2 = 22.4 liters, and 1.36 moles = 1.36 moles x 22.4 L/mole = 30.5 liters of O2 needed.
J.R. S.
tutor
If you take chemistry, you should memorize this value of 22.4 liters per mole of any gas at STP. The way it is determined is from the ideal gas law of PV = nRT. So, if at STP, then T = 273K and P = 1 atm. R is a constant of 0.0821 L-atm/K-mol and n is moles, which we will set at 1 mole. Solving for volume (V), you have V = nRT/P = (1)(0.0821)(273)/(1) = 22.4 liters
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05/29/18
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05/29/18