Question

At some altitude above the Earth’s surface, the density of air molecules is3.3×10^13 molecules/cm^3. At this altitude, the temperature is −44°C.

What is the mean free path of air molecules at this altitude? Assume a molecular diameter of 2.1×10^-8??.

What is the pressure at this altitude?

Answer #1

Mean free path ( using )

where is number of molecules per unit volume,

is cross-sectional area ,

Diameter of air molecules

Temperature of air molecules

Mean free path is

Pressure at this altitude is

a) The stratosphere extends to 50 km above the Earth’s surface,
where P = 0.085 kPa and T = 18.3° C.
What is the mean free path and collision frequency of N2 at this
altitude?
b) Describe the variation in mean free path with temperature for
a gas at constant volume?

Consider a gas of nitrogen molecules at 20°C with a particle
density of 2.7 ×1019 molecules/cm3. The molar mass of
nitrogen molecules is 28 g/mol.(a) What is the rms speed of the
nitrogen molecules?(b) At what temperature will the rms speed be
half that value?(c) What is the average translational kinetic
energy of these molecules at 20°C? (d) The mean free path of the
nitrogen molecules is 0.80×10−5 cm. What is the molecular radius of
a nitrogen molecule?

1. Determine the absolute pressure and the air density in
Earth’s atmosphere at the CN Tower’s observation deck, 342m above
the ground (and Toronto is a further 76 m above sea level), as a
percentage of the value at sea level. Assume the average mass of an
air molecule is 4.8 × 10−26 kg and that the temperature on a nice
sunny Toronto day is 25°C.

At what frequency would the wavelength of sound in air be equal
to the mean free path of oxygen molecules at 1.2 atm pressure and
-1.6°C? Take the diameter of an oxygen molecule to be 3.1 ×
10-8 cm and the speed of sound to be 340 m/s.

The density of uncompressed air is 1.293 kg/m3, and
one mole of air (containing Avogadro's number of molecules) has a
mass of 28.94 g.
a) Use the density and the volume of the uncompressed air 45 cc to
determine the mass of the air in the syringe,
mair, in grams. (You will have to do some unit
conversions.)
mair = ______ g
b)Use the mass of one mole of air and Avogadro's number to
determine N, the number of molecules in...

On a hot summer day, the density of air at atmospheric pressure
at 34.5°C is 1.1242 kg/m3.
(a) What is the number of moles contained in 1.00 m3 of an ideal
gas at this temperature and pressure? mol
(b) Avogadro's number of air molecules has a mass of 2.82 ✕ 10−2
kg. What is the mass of 1.00 m3 of air? (Assume air is an ideal
gas.) kg
(c) Does the value calculated in part (b) agree with the stated...

A vacuum chamber has a base pressure of 10-6 Torr. Assuming that
this is dominated by N2 gas where the diameter is 0.44 nm and
molecular mass of 28, (a) What is the gas density, the mean free
path, the molecule flux at 300 K? (b) What is the partial pressure
of O2 that produce a ratio 10-9 of the N2 flux to O2 flux at the
same temperature? Considering them have identical diameters

A long 8-cm-diameter steam pipe whose external surface
temperature is 90°C passes through some open area that is not
protected against the winds. Determine the rate of heat loss from
the pipe per unit of its length when the air is at 1 atm pressure
and 7°C and the wind is blowing across the pipe at a velocity of 47
km/h. The properties of air at 1 atm and the film temperature of
(Ts + T∞)/2 = (90 + 7)/2...

At the surface of Venus the average temperature is a balmy 460
∘C due to the greenhouse effect (global warming!), the pressure is
92 Earth-atmospheres, and the acceleration due to gravity is 0.894
gEarth. The atmosphere is nearly all CO2 (molar mass 44.0g/mol) and
the temperature remains remarkably constant. We shall assume that
the temperature does not change at all with altitude. Part
A What is the atmospheric pressure 2.50 km above the
surface of Venus? Express your answer in...

Taylor enjoys swimming in the pool. At 3 m below the surface,
she blows some bubbles of air.
As these bubbles rise up toward the surface of the pool, what
happens to their size?
Assume that its temperature remains constant. (Hint: an air
bubble underwater has the same pressure as that of the surrounding
water.)
the bubbles get bigger.
the bubble size may increase or decrease depending on the rate
they rise.
the bubble size remains constant. the bubbles get...

ADVERTISEMENT

Get Answers For Free

Most questions answered within 1 hours.

ADVERTISEMENT

asked 31 minutes ago

asked 1 hour ago

asked 1 hour ago

asked 1 hour ago

asked 2 hours ago

asked 2 hours ago

asked 2 hours ago

asked 2 hours ago

asked 2 hours ago

asked 3 hours ago

asked 3 hours ago

asked 3 hours ago