Question

What will be the value of 'A+B+C' if the following reaction is balanced?

${\mathrm{AFeCl}}_3\left(\mathrm{aq}\right)+\mathrm{BMgO}\left(s\right)🡪{\mathrm{Fe}}_2{O}_3\left(s\right)+{\mathrm{CMgCl}}_2\left(\mathrm{aq}\right)$

Answer 1

To find the value of A,B and C, we need to do the balancing of the given equation.

Number of Fe atoms on the reactant side: 1
Number of Fe atoms on the product side: 2

So we will multiply 2 on the left side to $\mathrm{FeCl}3$. Hence it will become;

$2{\mathrm{FeCl}}_3\left(\mathrm{aq}\right)+\mathrm{MgO}\left(s\right)🡪{\mathrm{Fe}}_2{O}_3\left(s\right)+{\mathrm{MgCl}}_2\left(\mathrm{aq}\right)$

Number of Cl atoms on the reactant side: 6 (2 X 3)
Number of Cl atoms on the product side: 2

So we will multiply 3 on the right side to $MgC{l}_2$. Hence it will become;

$2FeC{l}_3\left(aq\right)+MgO\left(s\right)🡪F{e}_2{O}_3\left(s\right)+3MgC{l}_2\left(aq\right)$

Now, the number of Mg atoms are not balanced. In order to balance it, we will multiply 3 to MgO.

$2{\mathrm{FeCl}}_3\left(\mathrm{aq}\right)+3\mathrm{MgO}\left(s\right)🡪{\mathrm{Fe}}_2{O}_3\left(s\right)+3{\mathrm{MgCl}}_2\left(\mathrm{aq}\right)$

Hence the equation is balanced and we also identified the value of A, B, and C, which are 2, 3, and 3 respectively.
So A+B+C =8.