Question

What is the mass of 1.25 L of ammonia gas at STP

Answer 1

Answer:

mass 1.25 Liters NH₃(gas) = 0.949 grams (3 sig-figs)

Explanation:

At STP (Standard Temperature-Pressure conditions => 0°C(=273K) and 1atm pressure,  1 mole any gas will occupy 22.4 Liters.

So, given 1.25 Liters ammonia gas at STP, convert to moles then multiply by formula wt. (17g/mole gives mass of NH₃.

moles NH₃(gas) = 1.25L NH₃(gas)/22.4L NH₄(gas)· NH₃(gas)mole⁻¹ = 0.0558 mole NH₃(gas).  

Converting to grams NH₃(gas) = 0.0558 mole NH₃(gas) x 17 g·mol⁻¹ = 0.949 grams NH₃(gas).