What is the mass in grams of 15 L of nitrogen gas at STP

Answer: m = 18.76 g N2

Explanation: To solve for the mass of N2 we will use the formula of Ideal Gas Law and find first the number of moles of N2.

PV = nRT, derive for n.

n = PV / RT, at STP pressure is 1 atm and temperature is 273 K.

n = PV/RT

= 1 atm (15 L) / 0.0821 L. atm / mole K (273 K)

= 0.67 mole N2

Next convert moles of N2 to mass using the molar mass of Nitrogen gas.

0.67 mole N2 x 28 g N2 / 1 mole N2

= 18.76 g N2