An expository is closer to research than a regular essay. You have one main point to make and then you either have information about the topic yourself or you research to find information to support you main point.
As a very simple example, let's say your main topic is that apple's are one of the best foods. You could use your own knowledge by explaining how good they taste. Then you could look on the Internet to find out where most U.S. apples are grown, if anyone knows how apple trees got to America and talk about Johnny Appleseed, whose story is that he planted apple trees all across the county.
This should be your structure:
The introduction is the first paragraph in the essay. The introduction contains the thesis statement, one sentence that summarizes the main idea of the essay. The body paragraphs follow the introduction and explain the main topics. Lastly, the conclusion is the final paragraph that restates the main topics and and the thesis. Every expository essay contains these features, in this order.
The rate and direction of reactions are greatly influenced by the Law of Mass action or molecular concentration because they relate to the same principle
The metric system measures mass in grams or kilograms, distance in meters or kilometers, and volume in liters. It measures temperature in Kelvin or Celsius degrees instead of the Fahrenheit degrees used in the imperial system. The Basic Unit for Mass The metric system measures mass in grams.