Vegetable oils are useful in cooking
because of their high boiling points.
However this increases the energy
content of foods compared with
cooking in boiling water.
Vegetable oils are hardened by reacting them with hydrogen to
increase their melting points. This makes them solids at room
temperature which are suitable for spreading.
The hardening reaction takes place at 60 degrees
with a nickel catalyst. The hydrogen adds onto c=c
bonds in the vegetable oil molecules