What is the molecular formula for a 5-carbon hydrocarbon with one $\pi$ bond and one ring?

Verified step by step guidance

1. Step 1: Understand the problem. A 5-carbon hydrocarbon with one π bond and one ring indicates that the molecule is cyclic and contains a double bond. This means it is an unsaturated hydrocarbon.
2. Step 2: Recall the general formula for hydrocarbons. Saturated hydrocarbons (alkanes) follow the formula C_nH_2n+2. However, the presence of a ring and a π bond reduces the number of hydrogens.
3. Step 3: Account for the ring. A ring introduces one degree of unsaturation, which reduces the hydrogen count by 2. The formula for a 5-carbon ring without any double bonds would be C₅H₁₀.
4. Step 4: Account for the π bond. A double bond introduces another degree of unsaturation, further reducing the hydrogen count by 2. Subtract 2 hydrogens from the formula in Step 3.
5. Step 5: Combine the information. The molecular formula is determined by considering the 5 carbons, the reduction in hydrogens due to the ring, and the reduction due to the π bond. Write the final molecular formula as C₅H₈.

Key Concepts

Hydrocarbons

Hydrocarbons are organic compounds consisting entirely of hydrogen and carbon atoms. They can be classified into aliphatic (straight or branched chains) and aromatic (ring structures). Understanding the structure of hydrocarbons is essential for determining their molecular formulas and properties.

Unsaturation and π Bonds

Unsaturation in organic chemistry refers to the presence of double or triple bonds between carbon atoms, indicated by π (pi) bonds. Each π bond reduces the number of hydrogen atoms that can be attached to the carbon skeleton. In this case, the presence of one π bond suggests that the hydrocarbon is unsaturated, affecting its molecular formula.

Cyclic Compounds

Cyclic compounds are organic molecules that contain a ring structure. The presence of a ring can influence the molecular formula and the degree of unsaturation. For a hydrocarbon with a ring and a π bond, the ring structure contributes to the overall count of carbon and hydrogen atoms, which is crucial for deriving the correct molecular formula.