A 75.0 l steel tank at 20.0°c contains acetylene gas, c2h2, at a pressure of 1.39 atm. assuming ideal behavior, how many grams of acetylene are in the tank?

we can use the ideal gas law equation to find the number of moles of acetylene gas in the tank

PV = nRT

where

P - pressure - 1.39 atm x 101 325 Pa/atm = 140 842 Pa

V - volume - 75.0 x 10⁻³ m³

n - number of moles

R - universal gas constant - 8.314 Jmol⁻¹K⁻¹

T - temperature in kelvin - 20 °C + 273 = 293 K

substituting these values in the equation

140 842 Pa x 75.0 x 10⁻³ m³ = n x 8.314 Jmol⁻¹K⁻¹ x 293 K

n = 4.34 mol

molar mass of acetylene - 26 g/mol

mass of acetylene present - 4.34 mol x 26 g/mol = 112.84 g

mass of acetylene present - 112.84 g