5.6L of gas at STP weighs equal to 8g.The vapor density of the gas is
STP = "standard temperature and pressure" as a temperature of 273.15 K (0 °C, 32 °F) and an absolute pressure of 100 kPa (14.504 psi, 0.986 atm, 1 bar). R = 8.314 L*kPa / K*mol pV = nRT = mRT/M Vapour density is the density of a vapour in relation to that of hydrogen. Therefore: vapour density = molar mass of gas / molar mass of H2 = molar mass of gas / 2.0016 Molar mass is
M = mRT / pV = 8g * 8.314L*kPa/K*mol * 273.15K / 100kPa * 5.6L = 32 g/mol vapour density = 32g/mol / 2g/mol = 16 The vapor density of the gas is 16.