Question

What are the empirical formulas for $C_9{H}_{20}$ , $P_4{O}_{10}$ , and $B_2{H}_6$ ?

Answer 1

Hint :Empirical formula of a compound depicts the simplest whole number ratio of the atoms present in a compound while molecular formula depicts the number of every atom present in a molecule. On the other hand, the structural formula depicts how atoms present in a molecule are being bonded to one another.

Complete Step By Step Answer:
Molecular formula represents the exact number of all of the atoms present in a molecule or compound. But, empirical formula represents the ratio of those atoms in a molecule or compound. Thus we can say that the relationship that exists between the molecular formula and the empirical formula can be represented as follows:
 $Molecularformula=(Empiricalformula{)}_n$
Where n refers to an integer
In the given question, we are provided with the molecular formula of three different compounds and we have to find out the empirical formula of these compounds. In order to find out the empirical formula from the molecular formula, we will divide the subscripts by the same integer to attain the smallest whole number. Let us find the empirical formula of each compound one by one:
1) $C_9{H}_{20}$ : The empirical formula will be same i.e. $C_9{H}_{20}$ as none of the integers except 1 is available in order to divide 9 and 20 to obtain the smaller whole numbers.
2) $P_4{O}_{10}$ : The empirical formula will be: $P_{{\displaystyle \frac{4}{2}}}{O}_{{\displaystyle \frac{10}{2}}}=P_2{O}_5$ which will be obtained by dividing each subscript by 2.
3) $B_2{H}_6$ : The empirical formula will be: $B_{{\displaystyle \frac{2}{2}}}{H}_{{\displaystyle \frac{6}{2}}}=B{H}_3$ which will be obtained by dividing each subscript by 2.
Hence, $C_9{H}_{20}$ , $P_2{O}_5$ and $B{H}_3$ are the empirical formulas for $C_9{H}_{20}$ , $P_4{O}_{10}$ , and $B_2{H}_6$ respectively.

Note :
If we know the molar mass of any unknown compound, we can find the molecular formula of that compound from its empirical formula by comparing the empirical formula mass with the molar mass of the compound.