The complete combustion of 1 mole of pentane, #C_5H_12#, will require how many moles of oxygen, #O_2#?

Answer 1

#8# #"mol O"_2#

We're asked to find the number of moles of #"O"_2# needed to completely combust #1# #"mol C"_5"H"_12#.

In order to accomplish this, we must first write the chemical equation for the reaction using the standard formula for a combustion reaction involving hydrocarbons:

#"hydrocarbon"color(white)(l) + "oxygen" rarr "carbon dioxide" + "water (vapor)"#

Thus

#"C"_5"H"_12(l) + "O"_2(g) rarr "CO"_2(g) + "H"_2"O"(g)" "# (unbalanced)
Let's now balance this equation. We'll first put a "#5#" in front of the #"CO"_2# to balance the carbons:
#"C"_5"H"_12(l) + "O"_2(g) rarr 5"CO"_2(g) + "H"_2"O"(g)" "# (unbalanced)
Now we'll put a "#6#" in front of #"H"_2"O"# to balance the hydrogens:
#"C"_5"H"_12(l) + "O"_2(g) rarr 5"CO"_2(g) + 6"H"_2"O"(g)" "# (unbalanced)
We now have #2# oxygens on the left side and #16# on the right side. Putting an "#8#" in front of #"O"_2# balances the equation:
#ul("C"_5"H"_12(l) + 8"O"_2(g) rarr 5"CO"_2(g) + 6"H"_2"O"(g)#
Now, we can realize that the stoichiometric ratio of pentane to oxygen is #1:8# (from coefficients).
Therefore, in order to completely combust #1# #"mol pentane"#, we must use #color(red)(ul(8color(white)(l)"mol O"_2#.
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Answer 2

One mole of pentane, C3H2O₂, will require 8.5 moles of oxygen, O₂, to burn completely.

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Answer from HIX Tutor

When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.

When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.

When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.

When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.

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