The lowest pressure attainable using the best available vacuum techniques is about 10−12 n/m2. part a at such a pressure, how many molecules are there per cm3 at 2 ∘c?

Number of molecules: N = 263.31

Some of the laws regarding gas can apply to ideal gas (volume expansion does not occur when the gas is heated),:

So that the three laws can be combined into a single gas equation, the ideal gas equation

In general, the gas equation can be written

where

P = pressure, atm , N/m²

V = volume, liter

n = number of moles

R = gas constant = 0.082 l.atm / mol K (P= atm, v= liter),or 8,314 J/mol K (P=Pa or N/m2, v= m³)

T = temperature, Kelvin

n = N / No

n = mole

No = Avogadro number (6.02.10²³)

n = m / m

m = mass

M = relative molecular mass

Known

P = 10−12 N / m2

V = 1 cm3 = 10-6 m3

T = 2 ºC = 2 + 273 = 275 K

R = 8,314 J / mol. K

then the number of molecules (N):

N = n x No

N = 4,374.10⁻²² x 6.02.10²³

N = 263.31

Which equation agrees with the ideal gas law

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Which law relates to the ideal gas law

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