Question

Please help me with this problem and what is the reaction type?

Answer 1

Let's first count how many atoms of each element we have on each side of the reaction.

Reagent side

Mg --->1 atom

Fe ---> 2 atoms

O ---->3 atoms

Product side

Mg --->1 atom

Fe ---->1 atom

O ----> 1 atom

We see that we have three oxygens on the reactant side and one on the product side, therefore we place the coefficient 3 in front of the MgO molecule:

$Mg+Fe_2O_3\rightarrow Fe+3Mg_{}O$

Now we balance the Mg atoms that changed, we have 3 atoms in the products, so we put the coefficient 3 in front of Mg

$3Mg+Fe_2O_3\rightarrow Fe+3Mg_{}O$

And finally we need to balance the iron, we have 2 iron atoms in the reactants, so we put the coefficient 2 in front of the iron molecule:

$3Mg+Fe_2O_3\rightarrow2Fe+3Mg_{}O$

Now we have on each side of the reaction:

Mg ---3 atoms

Fe ----2 atoms

O ---3 atoms

Now the reaction is balanced.

We have a substitution reaction because Mg trades place with Fe