The vapor pressure of pure methanol, CH3OH, is 94.0 torr at 20ºC, and the vapor pressure of pure ethanol, CH3CH2OH, is 44.0 torr at the same temperature. If a solution of these two liquids has a total vapor pressure of 65.5 torr at 20ºC, what is the mole fraction of methanol in that solution? (Assume that this is an ideal solution.)

Hot air balloons float in the air because of the difference in density between cold and hot air. in this problem, you will estimate the minimum temperature the gas inside the balloon needs to be, for it to take off. to do this, use the following variables and make these assumptions: the combined weight of the pilot basket together with that of the balloon fabric and other equipment is w. the volume of the hot air inside the balloon when it is inflated is v. the absolute temperature of the hot air at the bottom of the balloon is th (where th> tc). the absolute temperature of the cold air outside the balloon is tc and its density is ďc. the balloon is open at the bottom, so that the pressure inside and outside the balloon is the same. as always, treat air as an ideal gas. use g for the magnitude of the acceleration due to gravity.

This is a characteristic of the elements in the periodic table that shows a pattern. it may increase or decrease across or down the table.

Long term exposure to waves can cause sunburns and skin cancer. a) visible b) infrared c) gamma rays d) ultraviole