ORG CHEM | Properties of Organic Compounds

Alkanes’ Boiling Points

The boiling point increases with the number of carbon atoms in the chain, as this increases the surface area, leading to stronger intermolecular forces that require more energy to break.

Branching Affecting Alkanes’ Boiling Points

branching lowers the surface area, leading to weaker intermolecular forces, lowering the boiling point.

Alkane’s Melting Points

Melting points follow a similar trend to boiling points that is less predictable due to differences in molecular packing.

Density and Solubility of Alkanes

• the nonpolar nature of alkanes makes them insoluble in water and soluble in organic compounds

• it is less dense than water, ranging from 0.6 to 0.8 g/mL; so it floats in water

State of Matter of Small Alkanes

Compounds with a chain of 1-4 carbons are usually gases

State of Matter of Medium-chain Alkanes

Compounds with a chain of 5-17 carbons are usually liquids

State of Matter of Long-chain Alkanes

Compounds with a chain of at least 18 carbons are usually solids

Fat-soluble Vitamins

• nonpolar due to long hydrocarbon chains, allowing them to dissolve and be stored in fatty tissues and the liver

• they do not need to be consumed as frequently

• toxicity could occur if consumed in excess

• examples include Vitamins A, D, E, and K

Water-soluble Vitamins

• polar due to presence of hydroxyl groups, allowing them to dissolve in water

• they need to be consumed as frequently since they are absorbed quickly and excreted rapidly in urine

• toxicity is not as much of a concern but deficiencies happen more easily

• examples include Vitamins C and B-complex vitamins