Question

What is the molecular formula for each of the following?

1. a 4-carbon hydrocarbon with two p bonds and no rings
2. a 10-carbon hydrocarbon with one p bond and 2 rings

Short answer

We have to find the molecular formula for each of the following-

1. C₄H₆
2. C₁₀H₁₆

Step-by-step solution

What is p bond

When formation of double bond or triple bond occurs then there will be the presence of p bond. In double bond there is one p bond and in triple bond there is two p bonds. p bond is formed with the help of two electrons so when p bond is formed two hydrogens will become less than the simple hydrocarbon chain.

When ring formed then also two hydrogen will become less from the simple hydrocarbon chain.

How to find molecular formula

1. For a 4 carbon hydrocarbon with no p bonds and no rings, C_nH_{2n + 2} = C₄H₁₀. A 4-carbon hydrocarbon with two p bonds and no ring has four fewer hydrogens, because two hydrogens are subtracted for every p bond or ring in the molecule. Therefore, the molecular formula is C₄H₆.
2. For a 10 carbon hydrocarbon with no p bonds and no rings, C_nH_{2n + 2} = C₁₀H₂₂. A 10-carbon hydrocarbon with one p bond and two rings has six fewer hydrogens, because two hydrogens are subtracted for every p bond or ring in the molecule. Therefore, the molecular formula is C₁₀H₁₆.