Question

Margarine is made by hydrogenating liquid vegetable oils so that they take on the consistency of butter. Which of the following is the chemical basis for this change from a liquid to a solid?

1) Hydrolysis
2) Oxidation
3) Polymerization
4) Hydrogenation

Answer 1

Hydrogenation is the chemical basis for the conversion of margarine from a liquid to a solid, involving the addition of hydrogen to the fatty acids in vegetable oils, increasing the melting points and resulting in a semisolid product.

Step-by-step explanation:

The chemical basis for the change of margarine from a liquid to a solid is hydrogenation. This process involves the addition of hydrogen to the double bonds in the fatty acids of vegetable oils, which converts them into saturated fats. During hydrogenation, hydrogen gas is bubbled through the liquid oil in the presence of a catalyst such as nickel (Ni), platinum (Pt), or palladium (Pd).

This reaction converts the unsaturated fatty acids, which have lower melting points due to kinks caused by double bonds, into saturated fatty acids, which have straight chains that can pack more tightly and thus have higher melting points. As a result, the oil becomes semisolid at room temperature, resembling the consistency of butter.