Respuesta :
Convert all the gases from grams to moles using their molar masses first. Remember that nitrogen and oxygen exist as DIATOMIC gases.
O2 - 25 g / 32 g/mol = 0.78 mol O2
N2 - 15 g / 28.02 g/mol = 0.54 mol N2
He - 10 g / 4.0 g/mol = 2.5 mol He
Add all the moles of gases.
0.78 + 0.54 + 2.5 = 3.82 moles
Divide O2 moles by total moles.
0.78/3.82 = 0.20
O2 - 25 g / 32 g/mol = 0.78 mol O2
N2 - 15 g / 28.02 g/mol = 0.54 mol N2
He - 10 g / 4.0 g/mol = 2.5 mol He
Add all the moles of gases.
0.78 + 0.54 + 2.5 = 3.82 moles
Divide O2 moles by total moles.
0.78/3.82 = 0.20
The statement, that describes the mole fraction of oxygen is "0.20."
What is mole fraction?
The mole fraction, often known as the molar fraction, is defined in chemistry as the amount of a constituent, nᵢ, divided by the total amount of all constituents in a mixture, nₜₒₜ. It denotes the number of moles of a certain component in the solution divided by the total number of moles in the solution.
In order to calculate the mole fraction, initially the moles of the substance to be calculated from the given mass.
Gram to mole conversion,
[tex]=Grams\;*\;\frac{1\;mol}{grams} \\Moles of O2,25\;g\;*\;\frac{1\;mol}{32\;g}\;=\;0.78\;mol\;O2\\Moles of N215\;g\;*\;\frac{1\;mol}{28.02\;g}\;=\;0.54\;mol\;O2\\Moles of He10\;g\;*\;\frac{1\;mol}{4.0\;g}\;=\;2.5\;mol\;He[/tex]
Now, adding all the moles of gases0.78 + 0.54 + 2.5 = 3.82 moles.
Mole fraction of oxygen comes out to be,
[tex]Mole\; fraction\;=\frac{Amount \;of\;the\;substance}\\{Total\;moles} \\Mole\;fraction\;=\frac{0.78\;mol\;O2}{3.82 \;mol} =0.204.[/tex]
Hence the correct answer is 0.20.
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