Question

What is the molecular formula for a compound that has an empirical formula of ${C_3}{H_7}$ and a molar mass of $86.2g/mol$?
A. ${C_9}{H_{21}}$
B. ${C_6}{H_{14}}$
C. ${C_3}{H_7}$
D. None of the above

Answer 1

Hint: In chemistry, the empirical method of a chemical compound is the best superb integer ratio of atoms present in a compound. A simple instance of this idea is that the empirical formulation of sulfur monoxide, or $SO$, might virtually be $SO$, as is the empirical system of disulfur dioxide, ${S_2}{O_2}$.
Complete step by step solution:
Let the molecular formula of the compound is ${({C_3}{H_7})_n}$
Given molar mass of compound=
Molar mass of ${({C_3}{H_7})_n} = n(3 \times 12 + 7) = n(43)$
Then $n(43) = 86.2$
So $n = 2$
So, molecular formula is ${({C_3}{H_7})_2} = {C_6}{H_{14}}$

So the correct answer is B.

Additional information:
Molecular formulas describe the exact number and type of atoms in a single molecule of a compound. The constituent elements are represented by their chemical symbols, and the range of atoms of every detail found in every molecule is proven as a subscript following that detail’s symbol. The molecular system expresses information about the proportions of atoms that represent a specific chemical compound, the usage of a unmarried line of chemical element symbols and numbers. Sometimes it is usually other symbols, such as parentheses, dashes, brackets, and plus and minus signs and symptoms.
For organic compounds, carbon and hydrogen are listed as the first elements inside the molecular method, and they're accompanied by means of the remaining factors in alphabetical order. For instance, for butane, the molecular system is ${C_4}{H_{10}}$. For ionic compounds, the cation precedes the anion in the molecular system. For instance, the molecular method of sodium fluoride is $NaF$.

Note:
The molecular system, alternatively, suggests the quantity of every sort of atom in a molecule. The structural method indicates the association of the molecule. It is likewise viable for special kinds of compounds to have equal empirical formulation. Samples are analyzed in particular elemental evaluation exams to determine what percentage of a selected detail the pattern is composed of.