What variable is it? independent, dependent , control, or constants?

I am doing a experiment. In which i am boiling a chicken bouillon in water. I am placing them on 3 petri dishes. After that, in one i am placing vinegar ( in order to act as a preservative) . In another i am placing salt (act as another preservative) and the last petri dish i am not placing any thing. What would be the independent, the dependent, the control. and the constant ? Please help me. I want to make sure of my answers. Thank you :)What variable is it? independent, dependent , control, or constants?
Well the control is the one you are leaving alone, since it is what would happen naturally without you adding things or changing things (the definition of a control). A constant is anything that does not change, like the fact that you use chicken bouillon in water for all three, or that they are all in petri dishes. The independent variable is the one that you are changing, presumably to test your hypothesis - in this case it is what you add (vinegar or salt or nothing). The dependent variable is called that because it depends on the independent variable - it is what changes/happens depending on what the independent variable is. Basically it is your data, what you are collecting to see if it backs up your hypothesis.