Question

Define cryoscopic constant.
Give the IUPAC name of the given compound.

Answer 1

First we have to detect the parent chain of the given compound, then the substituent groups, and name them alphabetically with numbers the same as the carbon they are attached to.

Complete answer:
1. Let’s start with explaining the cryoscopic constant; it is the depression of the freezing point of the solvent produced on dissolving one mole of a substance in it. It is also known as the molal constant. It is denoted by and helps in relating the molality and freezing point depression.
2. Now, coming to IUPAC’s name, IUPAC is the International Union of Pure and Applied Chemistry which is responsible for naming compounds and giving standards for chemistry. The following are the steps that are used while naming the organic compound.
Detect the parent chain
Find the substituents
Identify the functional group (if there is one)
Name the functional group
Number your substituents on the same number as on the carbon alphabetically.

Now the compound given to us is having a parent chain of 5 carbons with a methyl group attached at 3rd carbon. Two bromine and one chlorine group are also present at 3rd, 2nd, and 1st carbon respectively. Therefore, we can write the name of the compound as $2,3 - dibromo - 1 - chloro - 3 - methyl{\text{ }}pentane$.
Hence, the IUPAC name of the given compound is $2,3 - dibromo - 1 - chloro - 3 - methyl{\text{ }}pentane$

Note:
We must know that the IUPAC is the organization which standardizes the components related to chemistry. It is of most importance to have a standardized naming system for compounds hence IUPAC developed some rules in that regard so that if any new molecule is being discovered it can be named accordingly to simplify the naming for everyone.