Question

The formula and molecular mass of ethanol is:
A. ${C_3}{H_6}O = 34gmo{l^{ - 1}}$
B. ${C_2}{H_6}{O_2} = 62gmo{l^{ - 1}}$
C. ${C_2}{H_5}O = 45gmo{l^{ - 1}}$
D. ${C_2}{H_6}O = 46gmo{l^{ - 1}}$

Answer 1

Hint:The chemical formula is the short representation of the structural framework of the constituents of any chemical compound and which determines the physical and chemical properties to some extent by just having a glance of the chemical formula itself.

Complete step by step answer:
In order to determine the chemical formula of any compound, we must look for certain parameters in the compound. In the question, the given chemical compound is ethanol. According to the rules of IUPAC nomenclature, there are salient features that must have been used in naming the chemical compound, ethanol. They are:
(i) The prefix of the compound is ‘eth’ which represents the name of any compound consisting of two carbon atoms in the main parent chain. Thus, in short, we can simply say that the compound has two carbon atoms.
(ii) From the suffix of the chemical compound, it is clearly visible that the main functional group present here is alcohol because the suffix that is used here is ‘ol’ which signifies the presence of the corresponding functional group. There is a replacement of one hydrogen atom ($H$ ) with a hydroxyl group $( - OH)$ .
(iii) As we know that the carbon atom is a tetravalent atom. Thus, it should fulfill the remaining valencies with hydrogen atoms. Thus, for two carbon atom parent chains, it should have a total of 6 hydrogen atoms. But, as mentioned earlier, one hydrogen atom has been replaced by a hydroxyl group. Thus, the total number of hydrogen atoms (along with the one present in the hydroxyl group) will still remain six only.
Hence, the chemical formula of ethanol is ${C_2}{H_6}O$ .
In order to calculate the molecular mass of ethanol, we just need to add the atomic masses of the individual constituent atoms.
Hence, the molecular mass will be = $(2 \times 12) + (6 \times 1) + (1 \times 16) = 24 + 6 + 16 = 46g/mol$

The correct option is D. ${C_2}{H_6}O = 46gmo{l^{ - 1}}$

Note: Ethanol is an organic compound and is an alcohol with the chemical formula of ${C_2}{H_6}O$ and is represented by the actual structural formula ${C_2}{H_5}OH$ . It is the second member of the alcohol family after methanol and is used extensively in chemical laboratories and chemical industries.