Question
I'm trying to do an expirement that concerns having vitamins supplement some nutrients a plant needs. Basically, I going to build a hydroponic system so that I can test this expirement. I was looking at a recent article and this is what I understood: water takes compounds and seperates the ions. Wouldn't water seperate the ions of let's say Vitamin C (C6H8O6) and let the roots absorb it?

Answer
Vitamin C is indeed a water soluble molecule, and whereas it plays a role in humans to regulate the activity of many enzymes in the human body, it is not essential to plant growth.

C6H8O6 is 6 carbon molecules, 8 hydrogen molecules, and 6 oxygen molecules if my biology lessons serves me right ? Carbon, hydrogen, and oxygen plants get from carbon dioxide in the air and from water. E.g. it is like adding a cup of bottled water to the ocean to give fish something to drink. These nutrients are available in abundance.

Besides these 3 nutrients, plants require nitrogen, phosphorus, potassium, calcium, magnesium, sulfur, iron, and manganese and a number of other small micro nutrients such as zinc, boron, etc.

These micronutrients you can to some extend compare to our vitamins in the sence that they are supplements needed in small quantities but which can affect the health of the organism consuming them.

The macronutrients, however, besides carbon, hydrogen and oxygen, are supplied by fertilization and those nutrients you can compare to our "food ingrediences".

Plants, as opposed to humans and animals, actually take up (e.g. eat) food ingrediences. They will then combine these ingrediences inside them and PRODUCE THEIR OWN FOOD. This process is called photosynthesis during which the sun's rays are used as energy source to produce carbohydrates which is used for growth.

To grow the plant need some essential elements. As mentioned, carbondioxide and water will supply carbon,hydrogen and oxygen. All other nutrients are provided by fertilizing with compounds which contain the other nutrients needed.

These plant nutrients consist of molecules which are loosely bound to each other. When dissolved in water, these bonds are "split" when the abundance of water molecules "overwhelm" them and "pull them apart". The result is individual fertilizer ions which are "suspended" in water.

When the water enters the plant roots, the fertilizer ions are taken up at the same time. This is how fertilizer ends up inside the plants.