In three moles of ethane \((\text{C}_2\text{H}_6)\), calculate the following:
(i) Number of moles of carbon atoms.
(ii) Number of moles of hydrogen atoms.
(iii) Number of molecules of ethane.
(i) Number of moles of carbon atoms.
(ii) Number of moles of hydrogen atoms.
(iii) Number of molecules of ethane.
Solution and Explanation
(i) 1 mole of \((\text{C}_2\text{H}_6)\) contains 2 moles of carbon atoms.
Number of moles of carbon atoms in 3 moles of \((\text{C}_2\text{H}_6)\)
= 2 × 3 = 6
(ii) 1 mole of \((\text{C}_2\text{H}_6)\) contains 6 moles of hydrogen atoms.
Number of moles of carbon atoms in 3 moles of \((\text{C}_2\text{H}_6)\)
= 3 × 6 = 18
(iii) 1 mole of \((\text{C}_2\text{H}_6)\) contains 6.023 × 10 23 molecules of ethane.
Number of molecules in 3 moles of \((\text{C}_2\text{H}_6)\)
\(= 3 × 6.023 × 10^{ 23} = 18.069 × 10^{23}\)
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Concepts Used:
Molecular Mass of Polymers
It is described as the distribution rather than a specific number due to the occurrence of polymerization in such a way as to produce different chain lengths. Polymer MW is derived as follows:
\[M_{W} = \sum^{N}_{i=1} w_{i}MW_{i}.\]Where,
wi = the weight fraction of polymer chains having a molecular weight of MWi.
The MW is typically measured by light dispersing experiments. The degree of dispersing arises from the molecule size and, thus, molecular weight dispensation can be mathematically set on the total scattering created by the sample.