Prior to the discovery that freon-12 (cf 2 cl 2 ) was harmful to the earth’s ozone layer, it was frequently used as the dispersing agent in spray cans for hair spray, etc. its enthalpy of vaporization at its normal boiling point of − 29.2°c is 20.25 kj mol − 1 . estimate the pressure that a can of hair spray using freon-12 had to withstand at 40°c, the temperature of a can that has been standing in sunlight. assume that ∆ vap h is a constant over the temperature range involved and equal to its value at − 29.2°c.
At the normal boiling point, the vapor pressure of a liquid is equal to the atmospheric pressure, 1 atm. Because ΔHvap doesn't change, we can use the Clausius-Clayperon equation to determinate the pressure at the other temperature.
So, for p1 = 1 atm, T1 = -29.2ºC + 273 = 243.8 K, T2 = 40ºC + 273 = 313 K, R = 8.3145 J/molK (gas constant):
ln(p2/1) = (20250/8.3145)*(1/243.8 - 1/313)
ln(p2) = 2435.50424*9.068x10⁻⁴
ln(p2) = 2.2086
p2 = 9.10 atm
odds are decent that your handwriting right now looks a little bit different than it did five years ago, and will look different again in five more. when i look back through my notebooks from middle school to now, i see a long, slow progression from meticulous and teeny letters to bigger, sloppier ones, plus a few side detours: sometime in high school, for example, i decided those loopy cursive lowercase f’s were just the coolest, adopting them as the lone rep for cursive in my otherwise all-print handwriting.
you didnt put any of the following