1 m of air at a pressure of 1 atm is mixed with 0.1 m³ of carbon dioxide at 1.5 atm and the mixture is compressed so that its total volume is 1 m³. Estimate the concentration of the carbon dioxide in the mixture in (a) w/w, (b) w/v, (c) mole fraction at a temperature of 25°C. Mean molecular weight of air is 28.8 and of carbon dioxide 44.

In the ‘gas saturation method’ for the measurement of vapour pressure, a volume V of gas at temperature T and pressure P, is bubbled slowly through the liquid that is maintained at the same temperature T. The mass m lost from the liquid is measured and this can be related to the vapour pressure in the following way. (a) If the molar mass of the liquid is M, derive an expression for the mole fraction of the liquid vapour. (Hint: If it is assumed to be a perfect gas, the amount in moles of the input gas can be found from its pressure, temperature and volume.) (b) Hence derive an expression for the partial pressure of the liquid vapour, assuming that the gas remains at the total pressure P after it has passed through the liquid. (c) Then show that the vapour pressure p is given by p = AmP/(1 + Am), where A = RT/MPV. (d) The gas saturation method was used to measure the vapour pressure of geraniol (M = 154.2 g mol−1) at 110 °C. It was found that, when 5.00 dm3 of nitrogen at 760 Torr was…

Calculate density in the following cases : (a) Air (ideal gas) at temperature 0°C and pressure 2 atm (b) Helium (ideal gas) that fills a 10-m³ volume at temperature 25°C, whose gauge pressure reads 1.5 atm (c) Granular iron of spherical grains of average diameter D = 1mm packed in a 1-grain/mm3 arrangement (density of iron p = 9g/cm³). Assume that the void in each mm3 is filled with air. Discuss why the result is expected. Make the same computation if the average diameter of the spherical grains are D = 0.25 mm packed in a 64-grain/mm3 . Discuss why the result for the density of both arrangements is the same.