Question

What is the volume of 19.87 mol of ammonium chloride (`NH_4Cl`) at STP?

Answer 1

445.3 L of `NH_4Cl`

Explanation:

Since we are at STP, we would use the ideal gas law equation
`PxxV = nxxRxxT`.

• P represents pressure (must have units of atm)
• V represents volume (must have units of liters)
• n represents the number of moles
• R is the proportionality constant (has units of `(Lxxatm)/ (molxxK)`)
• T represents the temperature, which must be in Kelvins.

Now what you want to do is list your known and unknown variables. Our only unknown is the volume of `NH_4Cl`. Our known variables are P,n,R, and T.

Since we are at STP, the temperature is 273K and the pressure is 1 atm. We are given moles and the proportionality constant, R, is equal to 0.0821 `(Lxxatm)/ (molxxK)`
Now all we have to do is rearrange the equation and solve for V like so:
`V = (nxxRxxT)/P`
`V = (19.87molxx0.0821(Lxxatm)/(molxxK)xx(273K))/(1atm)`
`V = 445.3 L`