Question 1: A substance that is soluble in two liquids and makes an emulsion last longer is called what?

Question 2: What is the process called that reduces the size of particles so emulsions will last longer?

1. A substance that is soluble in two liquids and makes an emulsion last longer is called "Emulsifier".

2. The process that reduces the size of particles so emulsions will last longer is called "Homogenization".

Explanation:

Emulsifiers are additives which enable two liquids to mix around each other. Water and oil separate in a container, for an instance, but using an emulsifier can make the liquids blend along. It is widely used on various foods and beverages. Egg yolks and mustard are a few examples of emulsifiers.

Homogenization is the physical mechanism by which the fat molecules in milk are broken down because then they stay incorporated instead of segregated as cream. Majority of the milk sold in the United States is homogenized.