vapour density is also referred to as relative density. Why???
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Answered by
16
Hi friend,
The vapour density and the relative density are used to find the but both of them differed in some ways.
Vapour density:-
Vapour density is the measure of density of any GAS to the ratio of the density of Hydrogen.
vapour density = mass of n molecules of gas / mass of n molecules of hydrogen.
Relative density:-
The relative density is defined as the ratio of density of any substance to the density of standard substance.
Relative density= density of substance/density of standard substance.
For solids and liquids the standard substance is water.
Hope this helped you a little!!!
The vapour density and the relative density are used to find the but both of them differed in some ways.
Vapour density:-
Vapour density is the measure of density of any GAS to the ratio of the density of Hydrogen.
vapour density = mass of n molecules of gas / mass of n molecules of hydrogen.
Relative density:-
The relative density is defined as the ratio of density of any substance to the density of standard substance.
Relative density= density of substance/density of standard substance.
For solids and liquids the standard substance is water.
Hope this helped you a little!!!
Anonymous:
thanx a lot
My pleasure
Answered by
3
vapor density
The ratio of the mass of a given volume of one gas to the mass of an equal volume of another gas, typically hydrogen, at the same temperature and pressure.
Relative Vapour Density (RVD) is defined as the mass of a gas or vapour compared to air, which has an
arbitrary value of 1. If the value of the RVD of a gas is less than 1 then the gas is less dense than air and
hence will rise. The lower the density of the gas the faster it rises.
If the value of the RVD is greater than 1 then the gas is more dense than air and will sink.
To calculate the Relative Vapour Density of a Gas
RVD = Relative Molecular Mass (RMM) of Gas
Relative Molecular Mass (RMM) of Air
Air is a complex mixture of gases so in order to calculate a useable RMM the composition of air is assumed
to be:
Nitrogen 78% Relative Molecular Mass 28
Oxygen 21% Relative Molecular Mass 32
Argon 1% Relative Molecular Mass 40
The RMM of air is then calculated as the weighted average thus:
RMM of Air = RMM of N2 x 78 + RMM of O2 x 21 + RMM of Ar x 1
100 100 100
= 28 x 78 + 32 x 2 + 40 ≈ 29
100 100 100
Example of a RVD Calculation
To find the RVD of Carbon Dioxide:-
1. Calculate the RMM of Carbon Dioxide CO2
Relative Atomic Mass of Carbon is 12
Relative Atomic Mass of oxygen is 16
Therefore RMM of CO2 is 12 + (2 x 16) = 44
2. Calculate the RVD of CO2
RVD of CO2 = RMM CO2
RMM Air
RVD of CO2 = 44 = 1.52
29
The ratio of the mass of a given volume of one gas to the mass of an equal volume of another gas, typically hydrogen, at the same temperature and pressure.
Relative Vapour Density (RVD) is defined as the mass of a gas or vapour compared to air, which has an
arbitrary value of 1. If the value of the RVD of a gas is less than 1 then the gas is less dense than air and
hence will rise. The lower the density of the gas the faster it rises.
If the value of the RVD is greater than 1 then the gas is more dense than air and will sink.
To calculate the Relative Vapour Density of a Gas
RVD = Relative Molecular Mass (RMM) of Gas
Relative Molecular Mass (RMM) of Air
Air is a complex mixture of gases so in order to calculate a useable RMM the composition of air is assumed
to be:
Nitrogen 78% Relative Molecular Mass 28
Oxygen 21% Relative Molecular Mass 32
Argon 1% Relative Molecular Mass 40
The RMM of air is then calculated as the weighted average thus:
RMM of Air = RMM of N2 x 78 + RMM of O2 x 21 + RMM of Ar x 1
100 100 100
= 28 x 78 + 32 x 2 + 40 ≈ 29
100 100 100
Example of a RVD Calculation
To find the RVD of Carbon Dioxide:-
1. Calculate the RMM of Carbon Dioxide CO2
Relative Atomic Mass of Carbon is 12
Relative Atomic Mass of oxygen is 16
Therefore RMM of CO2 is 12 + (2 x 16) = 44
2. Calculate the RVD of CO2
RVD of CO2 = RMM CO2
RMM Air
RVD of CO2 = 44 = 1.52
29
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