what is the density of methane gas at 20 degree and 115kpa?
The density listed for CH4 at 20 C and 1 atm is 0.668 g/L (0.717 for ideal gas behavior). You can take the 0.668 measured as a real gas and convert to 115 kPa from 101.325 kPa.
0.668 x (115/101.325) = ? g/L