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wherecideal is the speed of sound in an ideal gas.R (approximately 8.3145 J·mol-1·K-1) is the molar gas constant.k is the Boltzmann constantγ (gamma) is the adiabatic index (sometimes assumed 7/5 = 1.400 for diatomic molecules from kinetic theory, assuming from quantum theory a temperature range at which thermal energy is fully partitioned into rotation (rotations are fully excited), but none into vibrational modes. Gamma is actually experimentally measured over a range from 1.3991 to 1.403 at 0 degrees Celsius, for air. Gamma is assumed from kinetic theory to be exactly 5/3 = 1.6667 for monoatomic molecules such as noble gases).T is the absolute temperature in kelvins.M is the molar mass in kilograms per mole. The mean molar mass for dry air is about .0289645 kg/mole.m is the mass of a single molecule in kilograms.
Thus we observe that for a monatomic gas, with three degrees of freedom:while for a diatomic gas, with five degrees of freedom (at room temperature):
[tqble]GasDensity (kg/m3)Speed (feet/sec)Standard Deviation (feet/sec)Air1.29291039.722.4Argon1.7837957.820.3Carbon Dioxide1.977812.423.0Propane2.009771.521.3
How about a good dose of hypothyroidism! (seriously)
Thus to reduce the speed of sound further, you probably require a gas with a large number of atoms, and a high atomic weight....I would guess that most molecules that are heavy enough to have a speed of sound 1/3rd the speed of air when a gas, would probably be too heavy to be gaseous at STP.
Quote from: Karen W. on 20/09/2007 00:09:31How about a good dose of hypothyroidism! (seriously)Probably taking steroids would have the same effect.
So there would be some slight drop in frequency when breathing propane.
Would that mean that having too much alcohol (C2H5OH, MW 46) in your breath would lower the pitch of your voice ?