Trans unsaturated fatty acids have which property?

Trans unsaturated fatty acids have which property?

• A. Straighter hydrocarbon tails, so they pack tightly
• B. Kinked tails
• C. Higher melting point
• D. More double bonds

Answer: (A)

When a fatty acid has a trans double bond, the two hydrogen substituents across the double bond lie on opposite sides, making the chain run more straight. This near-linear shape lets the fatty acid tails pack closely together, just like saturated fats do, which raises the temperature at which the fat melts. So the defining property of trans unsaturated fatty acids is straighter hydrocarbon tails that can pack tightly. The kinked tails describe cis fats, not trans; while a higher melting point can be true compared with cis fats under some conditions, the key distinguishing feature is the straighter tail geometry. More double bonds isn’t what defines trans fats, since the number of double bonds is not fixed by trans configuration.

When a fatty acid has a trans double bond, the two hydrogen substituents across the double bond lie on opposite sides, making the chain run more straight. This near-linear shape lets the fatty acid tails pack closely together, just like saturated fats do, which raises the temperature at which the fat melts. So the defining property of trans unsaturated fatty acids is straighter hydrocarbon tails that can pack tightly. The kinked tails describe cis fats, not trans; while a higher melting point can be true compared with cis fats under some conditions, the key distinguishing feature is the straighter tail geometry. More double bonds isn’t what defines trans fats, since the number of double bonds is not fixed by trans configuration.