Question

How would you find the volume of 7 moles of CH4 at standard temperature and pressure?

Answer 1

The volume of 7 moles of `"CH"_4"` at STP is approximately `"200 L"`.

Explanation:

STP is 273.15 K and 100 kPa.

Use the ideal gas law, `PV=nRT`, where `P` is pressure, `V` is volume, `n` is moles, `R` is the gas constant, and `T` is temperature.

`P="100 kPa"`
`V= ???`
`n="7 mol CH"_4"`
`R="8.3144598 L kPa K"^(−1) "mol"^(−1)"`
`T="273.15 K"`

Equation
`PV=nRT`

Solution
Rearrange the equation to isolate volume and solve.

`V=(nRT)/P`

`V=(7 cancel(mol) * 8.3144598"L" cancel"kPa" cancel"K"^(−1)""cancel"mol"^(−1) * 273.15cancel"K")/(100cancel"kPa")="159 L"="200 L CH"_4"`(rounded to one significant figure)