Question

Question #e0eda

Answer 1

There are `~~" 200 moles"` of air in the tank.

Explanation:

You would use the Ideal Gas Law:

`PV=nRT`

All of the variables you indicate in your question pertain to this equation, except for R, which is the gas constant, and which you might need to look up.

Organize your data:

Known

`P="20000 kPa"`

`V="25 L"`

`T="300 K"`

`R="8.3144598 L kPa K"^(−1) "mol"^(−1)"`
https://en.wikipedia.org/wiki/Gas_constant

Unknown: moles: `n` (moles)

Solution

Rearrange the ideal gas law equation to isolate `n` on the left side. Insert your data and solve.

`n=(PV)/(RT)`

`n=(20000color(red)cancel(color(black)("kPa"))xx25color(red)cancel(color(black)("L")))/(8.3144598 color(red)cancel(color(black)(" L")) color(red)cancel(color(black)(" kPa")) color(red)cancel(color(black)(" K"))^(−1) "mol"^(−1)xx300color(red)cancel(color(black)("K")))="200 mol air"` rounded to one sig fig