We use a spectrometer to help us determine what stars and planets are made of by passing a light through various chemical elements, different spectral patterns are created. By matching those patterns up to patterns generated in a laboratory environment we can tell what the composition of a distant star or planet is.

4 0

3 years ago

At what pressure will the mean free path in room-temperature (20?c) nitrogen be 1.5 m ?

kondaur [170]

In physical chemistry, the mean free path is the average distance between the atoms during collision. Its formula is

$Mean \ free \ path \ = \frac{RT}{ \sqrt{2} \pi d^{2} N_{A}P }$

where d is the diameter of the Nitrogen atom (d = 310 x 10^-7 m), Na is Avogadro's number (Na=6.022 x 10^23), R is the gas constant (8.314 J/mol-K), T is the absolute temperature (T= 20 + 273 = 293 K). Substituting the values,

$1.5 = \frac{(8.314)(293)}{ \sqrt{2} \pi (310 \ x\ 10^{-7} )^{2} (6.022 \ x\ 10^{23} )P }$
P = 6.32 x 10^-13 Pascals

6 0

3 years ago

What is the speed of a 2000 Hz sound wave in vacuum?

Aleks [24]

A sound wave can not value in a vacuum, so its speed is 0.
Sound waves are longitudinal and require a medium to pass through.

8 0

3 years ago