Question

In homologous series of aldehyde, the consecutive members of the series differ by the mass of:

Answer 1

Hint: We should know that homologous series is a sequence of compounds with the same functional group and similar chemical properties in which the members of the series can be branched or unbranched.

Step by step solution:
We should first define homologous series. A homologous series in organic chemistry is a group of organic compounds that differ from each other by one methylene ($C{{H}_{2}}$) group. For example, methane, ethane, and propane are part of a homologous series. The only difference among these molecules is that they have different numbers of $C{{H}_{2}}$ groups.
Each member of a homologous series is called a homologue, which can also be spelled ''homolog.'' For example, methane and ethane are homologues and belong to the same homologous series. They differ from each other by one $C{{H}_{2}}$ group. The formula of methane is $C{{H}_{4}}$ and the formula of ethane is ${{C}_{2}}{{H}_{6}}$.
Ethanal ($C{{H}_{3}}CHO$) and propanal ($C{{H}_{3}}C{{H}_{2}}CHO$) are two consecutive members of homologous series of aldehydes. In these compounds, the physical properties such as melting point, boiling point, density etc., gradually increase with the increase in the molecular weight. There is a difference of 14μ (unified mass) in the molecular masses of two nearest compounds of a series.
This is because, with the increase in the molecular mass of the compounds, the number of bonds also increases. Therefore, properties such as melting and boiling point, solubility, etc. that depend on the mass and the total number of bonds in a compound show a gradual change with an increase in molecular masses of the compounds. Chemical properties of the members of a homologous series are the same due to the fact that they all have the same functional groups in them.

Note: We should now know about homologous alcohols. They all contain the functional group –OH, which is responsible for the properties of alcohols. The first three alcohols in the homologous series are methanol, ethanol and propanol. They are highly flammable, making them useful as fuels. They are also used as solvents in marker pens, medicines, and cosmetics (such as deodorants and perfumes). Ethanol is the alcohol found in alcoholic drinks such as wine and beer. Ethanol is mixed with petrol for use as a fuel.