2HCl + Mg ---> H2 + MgCl2 How can I differ what is what?
2HCL=
Mg =
---
H2 =
MgC12 =
Frankly I don't know what you are asking? The left hand side (Mg and HCl) are the reactants. The right hand side (H2 and MgCl2) are the products.
HCl is hydrochloric acid
Mg is magnesium
H2 is hydrogen
MgCl2 is magnesium chloride.