Question

Two methods were descibed for determining the volume of the flask used for the molar mass determination. Which method will give a more precise determination of the volume? Why?

When two acceptable determinations of the weight of vapor needed to fill the flask have been obtained, remove the foil cover from the flask (do not discard) and clean out the flask. Fill the flask to the very rim with tap water, cover with the foil cover, and weigh the flask, cover, and water to the nearest 0.1 g. Determine the temperature of the tap water in the flask. Using the density of water at the temperature of the water in the flask and the weight of water the flask contains, calculate the exact volume of the flask. If no balance with the capacity to weigh the flask when filled with water is available, the volume of the flask may be approximated by pouring the water in the flask into a 1-L graduated cylinder and reading the water level in the cylinder Using the volume of the flask (in liters), the temperature of the boiling water bath (in kelvins), and the barometric pressure (in atmospheres), calculate the number of moles of vapor the flask is capable of containing. R=0.0821 L atm/mol K. PV RT Using the weight of unknown vapor contained in the flask (g), and the number of moles of vapor present (n), calculate the molar mass of the unknown liquid (M). M=g

Answer 1

Liven srit L Based PV Condition In = function i Because V. (T' all are value dependent - When these value will slightly change then volume is also Changed and we get less Precise value M = this method will give a more n Precise determination of the volume Because mass does not affected by any factor mass (weight) Remain Constent in all Conditions Hope this will help you Thank you very much Good luck PAGE IT