Question

If 3 moles of ethane $\text{(}{{\text{C}}_{2}}{{\text{H}}_{6}}\text{)}$ are given, calculate the following:
(i) Number of moles of carbon atoms.
(ii) Number of moles of the hydrogen atom
(iii) Number of molecules of ethane.

Answer 1

Hint: For this problem, we have to use the concept of the mole. If we know that in a one-mole of ethane how many moles of carbon and hydrogen are present then we can easily calculate the number of moles of carbon and hydrogen in 3 moles of ethane.

Complete Step-by-step answer:
- In the given question, we have to calculate the number of moles of carbon and hydrogen atom in 3 moles of ethane.
- As we know that ethane is a saturated hydrocarbon which is commonly known as methyl or dimethyl.
(i) We know that in 1 mole of ethane there are 2 moles of carbon atom because 2 carbon atoms are present in one molecule of ethane.
- Now, in 3 moles of ethane the total number of carbon atom will be:
$3\text{ }\times \text{ 2 = 6}$
- So, there are 6 moles of carbon atom present in 3 moles of ethane.
(ii) We know that in 1 mole of ethane there are 6 moles of hydrogen atoms because 6 hydrogen atoms are present in one molecule of ethane.
- Now, in 3 moles of ethane the total number of hydrogen atom will be:
$3\text{ }\times \text{ 6 = 18}$
- So, there are 12 moles of hydrogen atom present in 3 moles of ethane.
(iii) Here, we know that in one mole there are $6.022\text{ }\times \text{ 1}{{\text{0}}^{23}}$ Avogadro's number or particles like an atom, etc.
- So, in 3 moles of ethane, the total number of molecules will be $6.022\text{ }\times \text{ 1}{{\text{0}}^{23}}\text{ }\times \text{ 3 = 18}.066\text{ }\times \text{ 1}{{\text{0}}^{23}}$.
Therefore, there are 6 moles of the carbon atom, 12 moles of the hydrogen atom and $\text{18}.066\text{ }\times \text{ 1}{{\text{0}}^{23}}$ molecules of ethane.

Note: Avogadro's number tells us the total elementary particles that are present in a mole of any substance. A number of moles of any substance are defined as the ratio of the given mass to the molecular mass of the element. Do not confuse between the molecular formula of ethane and ethene.