HW Key part b

# HW Key part b - S25. Baseball reporters say that long fly...

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S25. Baseball reporters say that long fly balls that would have carried for home runs in July “die” in the cold air of October and are caught. The idea behind this observation is that a baseball carries better when the air is less dense. Dry air is a mixture of gases with an effective molar mass of 29.0 g/mol. a. Compute the density of dry air on a July day with the temperature is 95.0 °F and the pressure is 1.00 atm. Assume that dry air is an ideal gas. Its density is determined by combining the ideal gas equation with the relation n = m / M (where n is the number of moles, m is the mass of the gas and M is the molar mass of the gas) and the definition of density ( ρ = m / V ) and rearranging to give ρ = MP RT = (29.0 g/mol)(1.00 atm) (0.08206 L atm/mol K)(308.15 K) = 1.15 g/L b. Compute the density of dry air on an October evening when the temperature is 50.0 °F and the pressure is 1.00 atm. ρ = MP RT = (29.0 g/mol)(1.00 atm) (0.08206 L atm/mol K)(283.15 K) = 1.25 g/L c. Suppose that the humidity on the July day is 100%, so that the air is saturated with water vapor. Is the density of this hot, moist air less than, equal to, or greater than the density of the hot, dry air computed in part (a)? In other words, does high humidity favor the home run? Saturation the dry air with water vapor means adding a component to the mixture that has a molar mass less than the molar mass of either N 2 or O 2 , the main

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## This note was uploaded on 02/01/2011 for the course CHEM 111 taught by Professor Owens,g during the Fall '08 term at University of Utah.

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HW Key part b - S25. Baseball reporters say that long fly...

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