Explanation:
Given the following reaction:
__ NaOH + __ Fe(NO₃)₃ ---> __ Fe(OH)₃ + __ NaNO₃
A double replacement reaction is a type of chemical reaction where the two reactants exchange their ions to produce two new products.
A double replacement reaction has the following shape:
AB + CD ----> AC + BD
Which is similar to our reaction. NaOH and Fe(NO₃)₃ are exchanging their ions to form Fe(OH)₃ and NaNO₃.
So our reaction is a double replacement reaction.
Now we have to balance it.
__ NaOH + __ Fe(NO₃)₃ ---> __ Fe(OH)₃ + __ NaNO₃
The first step to balance a reaction is to dermine the number of atoms of each element that we have on both sides of the equation. In this case, since it is a double replacement reaction, it is easier to work with the ions or group of atoms that are being exchanged.
__ NaOH + __ Fe(NO₃)₃ ---> __ Fe(OH)₃ + __ NaNO₃
Na: 1 Na: 1
OH: 1 OH: 3
Fe: 1 Fe: 1
NO₃: 3 NO₃: 1
The Na atoms are already balanced since we have 1 atom of Na on each side of the equation. Then we have 1 OH group on the left side and 3 OH groups of the right. To balance it we have to change the coefficient for NaOH and write a 3 there.
3 NaOH + __ Fe(NO₃)₃ ---> __ Fe(OH)₃ + __ NaNO₃
Na: 3 Na: 1
OH: 3 OH: 3
Fe: 1 Fe: 1
NO₃: 3 NO₃: 1
Now, we balanced the OH but unbalanced the Na atoms. We have 3 atoms of Na on the left and 1 Na atom of the right. We can change the coefficient for NaNO₃ to balance it.
3 NaOH + __ Fe(NO₃)₃ ---> __ Fe(OH)₃ + 3 NaNO₃
Na: 3 Na: 1
OH: 3 OH: 3
Fe: 1 Fe: 1
NO₃: 3 NO₃: 3
Finally we have the same number of atoms of each element on both sides of the equation. The equation is balanced.
3 NaOH + Fe(NO₃)₃ ---> Fe(OH)₃ + 3 NaNO₃
Answer:
1. 3 NaOH + Fe(NO₃)₃ ---> Fe(OH)₃ + 3 NaNO₃
2. Double replacement.
