What is the pressure in atmospheres of 0.246 gram of hydrogen gas occupying a volume of 0.0500 liters at 21.0°C?

1 Answer
Oct 10, 2016

Answer:

The pressure of #"H"_2"# gas will be 58.9 atm, rounded to three significant figures.

Explanation:

You need the ideal gas law to answer this question.

https://jahschem.wikispaces.com/ideal+gas+law

First convert the mass of hydrogen gas #("H"_2")# to moles by dividing the given mass by its molar mass.

Molar mass #"H"_2"##=##(1.008"g/mol"xx2=2.016"g/mol")#.

Moles #"H"_2"#

#(0.246cancel"g H"_2)/(2.016cancel"g/mol H"_2")##=##"0.122 mol H"_2"#

Now you need to determine your known and unknown variables.

Known
#V="0.0500 L"#
#n="0.122 mol"#
#R="0.082057338 L atm K"^(-1) "mol"^(-1)"#
#T="21.0"^@"C"+"273.15=294.2K"#

Unknown
#P#

Solution
Rearrange the ideal gas equation to isolate #P# and solve.

#P=(nRT)/V#

#P=((0.122cancel"mol")xx(0.082057338 cancel"L" "atm" cancel"K"^(-1) cancel"mol"^(-1))xx(294.2cancel"K"))/(0.0500cancel"L")="58.9 atm"#
rounded to three significant figures