Question

What volume in liters does 0.136 g of O2 occupy at 20.0 degree C and 748 torr?

Answer 1

The volume will be `"0.104 L"`.

You're dealing with a sample of oxygen gas, `O_2`, at a certain temperature, `"20"^@"C"`, and pressure, `"748 torr"`. To solve for the volume it occupies, use the ideal gas law equation, `PV = nRT`.

Use oxygen's molar mass to determine th number of moles you have in that sample first

`0.136cancel("g") * "1 mole"/(32.0cancel("g")) = "0.00425 moles"`

Now plug all your values into the ideal gas law equation - do not forget to convert degrees Celsius to Kelvin and torr to atm

`PV = nRT => V = (nRT)/P`

`V = (0.00425cancel("moles") * 0.082(cancel("atm") * "L")/(cancel("mol") * cancel("K")) * (273.15 + 20)cancel("K"))/(748/760cancel("atm"))`

`V = "0.1038 L"`

Rounded to three sig figs, the answer will be

`V = color(green)("0.104 L")`