Definition - What does Reactant mean?
A reactant is one or more starting chemicals that molecularly interact with each other to form a new product. In the chemical reaction between iron and water that forms rust, iron and water are both reactants and rust (iron oxide) is the product.
Corrosionpedia explains Reactant
A typical reaction may be given by an equation of the form:
A + B → C
In this equation A and B are reactants and C is the product. However, there does not necessarily have to be multiple reactants in a reaction. In a decomposition reaction, such as:
C → A + B
C is the reactant, while A and B are the products.
By convention, reactants are always positioned on the left side of the arrow while products are on the right.
A typical corrosion reaction is:
2Fe(s) + O2(g) + 2H2O(1) → 2Fe2+(aq) + 4OH-(aq)