An unsaturated hydrocarbon is hydrogenated by adding one hydrogen molecule to form an alkane. If there are six carbon atoms in the hydrocarbon, the structural formula of the unsaturated hydrocarbon is:
Question 23 options:
a) CH3 – CH = CH – CH2 – CH2 – CH3
b) CH3 – CH2 – C º C – CH2 – CH3
c) CH3 – C = C – CH2 – CH2 – CH3
d) CH3 – CH2 – CH º CH – CH2 – CH3
e) CH3 – C = C – CH º CH – CH2
The correct answer is c) CH3 – C = C – CH2 – CH2 – CH3. This is because an unsaturated hydrocarbon contains at least one double bond between carbon atoms. In this case, the structural formula has a double bond between the second and third carbon atoms (CH3 – C = C – CH2 – CH2 – CH3).
To determine the structural formula of the unsaturated hydrocarbon, we need to consider the definition of an unsaturated hydrocarbon. An unsaturated hydrocarbon contains at least one double or triple bond between carbon atoms.
We are given that there are six carbon atoms in the hydrocarbon. Let's analyze the options provided:
a) CH3 – CH = CH – CH2 – CH2 – CH3: This option contains a double bond between the second and third carbon atoms. Since there is only one double bond, this is consistent with an unsaturated hydrocarbon.
b) CH3 – CH2 – C º C – CH2 – CH3: This option contains a triple bond between the third and fourth carbon atoms. Since there is only one triple bond, this is consistent with an unsaturated hydrocarbon.
c) CH3 – C = C – CH2 – CH2 – CH3: This option contains a double bond between the second and third carbon atoms. Since there is only one double bond, this is consistent with an unsaturated hydrocarbon.
d) CH3 – CH2 – CH º CH – CH2 – CH3: This option contains a triple bond between the third and fourth carbon atoms. Since there is only one triple bond, this is consistent with an unsaturated hydrocarbon.
e) CH3 – C = C – CH º CH – CH2: This option contains a double bond between the second and third carbon atoms and a triple bond between the fourth and fifth carbon atoms. Since there are two unsaturated bonds, this does not fit the definition of an unsaturated hydrocarbon with just one double bond.
After analyzing the options, the correct structural formula of the unsaturated hydrocarbon with six carbon atoms is:
a) CH3 – CH = CH – CH2 – CH2 – CH3
To determine the structural formula of the unsaturated hydrocarbon, we need to understand the concept of hydrogenation. Hydrogenation is a reaction in which hydrogen gas (H2) is added to a molecule, typically an unsaturated hydrocarbon, to convert it into a saturated hydrocarbon.
In this question, we are told that an unsaturated hydrocarbon is hydrogenated by adding one hydrogen molecule, which means that the unsaturated hydrocarbon has one double bond.
To find the structural formula, we examine each option and determine if it satisfies the given information.
a) CH3 – CH = CH – CH2 – CH2 – CH3: This molecule has one double bond, so it could be a candidate for the unsaturated hydrocarbon.
b) CH3 – CH2 – C º C – CH2 – CH3: This molecule has a triple bond, not a double bond, so it does not satisfy the given information.
c) CH3 – C = C – CH2 – CH2 – CH3: This molecule has one double bond, so it could be a candidate for the unsaturated hydrocarbon.
d) CH3 – CH2 – CH º CH – CH2 – CH3: This molecule has a triple bond, not a double bond, so it does not satisfy the given information.
e) CH3 – C = C – CH º CH – CH2: This molecule has two double bonds, not one double bond, so it does not satisfy the given information.
Comparing the options, we see that options a) and c) both have one double bond. However, option a) has six carbon atoms, which matches the given information that the hydrocarbon has six carbon atoms.
Therefore, the correct structural formula of the unsaturated hydrocarbon is:
a) CH3 – CH = CH – CH2 – CH2 – CH3