If 5.00 L of hydrogen gas measured at 20.0*C and 80.1 kPa is burned in an excess of oxygen, what mass under the same conditions, would be consumed?

1 Answer
Meave60
Jul 20, 2018

The mass of "H"_2" consumed is "0.331 g H"_2".

Explanation:

Use the equation for the ideal gas law to find the moles of hydrogen gas. Then determine the mass by multiplying the moles by its molar mass.

Ideal gas law

PV=nRT

Known

P="80.1 kPa"

V="5.00 L"

R="8.31447 L kPa K"^(-1) "mol"^(-1)

T="20.0"^@"C + 273.15"="293.2 K"

Unknown

moles, n

To determine moles "H"_2", rearrange the equation to isolate n. Plug in the known values and solve.

n=(PV)/(RT)

n=(80.1color(red)cancel(color(black)("kPa"))xx5.00color(red)cancel(color(black)("L")))/(8.31447color(red)cancel(color(black)("L")) color(red)cancel(color(black)("kPa")) color(red)cancel(color(black)("K"))^(-1) "mol"^(-1)xx293.2color(red)cancel(color(black)("K")))="0.164 mol H"_2"

To determine the mass of "H"_2" by multiplying the moles by its molar mass ("2.016 g/mol").

0.164color(red)cancel(color(black)("mol H"_2))xx(2.016"g H"_2)/(1color(red)cancel(color(black)("mol H"_2)))="0.331 g H"_2"

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