A Simple Guide On The Gram Molar Volume

Gram molar volume is the volume occupied by one mole of a substance. Gram molar volume of an ideal gas is 22.4 litres at STP (Standard Temperature and Pressure) or NTP (Normal Temperature and Pressure). 

For understanding it better let’s take an example,

The volume of 1 mole of H2 at STP = 22.4 L

STP = 22.4 L

The volume of ¼ mole of H2 =22.4/4

                                                  = 5.6 L

What is the 1 class mole concept?

The amount of substance which has equal to gram atomic mass is called a mole. 

1 mole of carbon atoms = 12 grams

It can also be defined as the amount of a substance (in grams) that contains 6.023 × 1023 units of that substance; therefore, 1 mole is the gram molecular weight of a substance:

Number of mole = weight of substance (in grams) / gram molecular weight

Numerical based on mole concept:

How many grams are there in 5.5 mol of sulphur?

First, we need to find molar mass then only we can convert mass into mole

Molar mass of sulphur = 32.0 g mol-1

Number of moles of sulphur = 5.50 mol

Mass of sulphur (in grams) = molar mass × number of moles

                                                 = 5.50 mol × 32.0 g mol-1 = 176.0 g sulphur

Calculate number of moles present in 64 g of oxygen 

Molar mass of oxygen = 32 g mol-1

Number of moles of oxygen = 64 g/ 32 g mol-1

=2.0 moles

What is the percentage of carbon, hydrogen and oxygen in ethanol?

Molecular formula of ethanol is C2H5OH

Molar mass of ethanol = (2 × 12.01 + 6 × 1.008 + 16.00) g

                              = 46.068 g

Mass percent of hydrogen = 6.048 g/ 46.068 g × 100

 = 13.13%

Mass percent of oxygen = 16.00g/ 46.068 g × 100

 = 34.73%

A compound contains 4.07% hydrogen, 24.27% carbon and 71.65% chlorine. Its molar mass is 98.96 g. What are its empirical formula and molecular formula?

In the 100 g sample of the above compound, 4.07g hydrogen, 24.27g carbon and 71.65g chlorine are present.

Moles of hydrogen = 4.07 g/ 1.008g = 4.04

Moles of carbon = 24.27 g /g12.01 = 2.021 

Moles of chlorine = 71.65g/ g35.453 = 2.021

Now, divide each of the mole values obtained above by the smallest number amongst them

2.021 is the smallest value, division by it gives a ratio of 2:1:1 for H:C:Cl . In case the ratios are not whole numbers, then they may be converted into the whole number by multiplying by the suitable coefficient.

Now, write down the empirical formula by mentioning the numbers after writing the symbols of respective elements CH2Cl is, thus, the empirical formula of the above compound

Molecular formula will be 

Determine empirical formula mass by adding the atomic masses of various atoms present in the empirical formula. 

For CH2Cl, empirical formula mass is 12.01 + (2 × 1.008) + 35.453 = 49.48g 

Dividing Molar mass by empirical formula mass

Molar mass/ empirical formula mass = 98.96g / 49.48 g

                                                                   = 2 = (n)

Empirical formula = CH2Cl 

n=2

molecular formula = C2H4Cl2

Conclusion:

It may be emphasised that the mole of a substance always contains the same number of entities, no matter what the substance may be. In order to determine this number precisely, the mass of a carbon–12 atoms were determined by a mass spectrometer and found to be equal to 1.992648 × 10–23 g. Knowing that one mole of carbon weighs 12 g, the number of atoms in it is equal to 12g/ mol 12C/1.992648 × 10-23 g/12C atom

= 6.0221367 × 1023 atoms/mol (Avogadro number)