This formula equation is unbalanced. BaCl2 (aq) + Na2CO3 (aq) Right arrow. BaCO3 (s) + NaCl (aq) Which coefficient should be placed in front of NaCl to balance this equation?

The coefficient that must be placed against NaCl to balance this equation is 2.

Explanation:

You have the unbalanced equation:

BaCl₂ (aq) + Na₂CO₃ (aq) → BaCO₃ (s) + NaCl (aq)

The law of conservation of matter states that since no atom can be created or destroyed in a chemical reaction, the number of atoms that are present in the reagents has to be equal to the number of atoms present in the products.

Then, you must balance the chemical equation. For that, you must first look at the subscripts next to each atom to find the number of atoms in the equation. If the same atom appears in more than one molecule, you must add its amounts.

Left side: 1 barium Ba, 2 chlorine Cl, 2 sodium Na, 1 carbon C and 3 oxygen O.

Right side: 1 barium Ba, 1 chlorine Cl, 1 sodium Na, 1 carbon C and 3 oxygen O.

In this case, carbon, barium and oxygen have the same amount on both sides, so it only remains to balance the chlorine and the sodium.

The coefficients in front of each molecule indicate the amount of each molecule for the reaction. This coefficient can be modified to balance the equation, just as you should never alter subscripts.

By multiplying the mentioned coefficient by the subscript, you get the quantity of each element present in the reaction.

To balance the chlorine and the sodium, you can modified the coefficients in front of the molecule NaCl as it's shown in the following:

BaCl₂ (aq) + Na₂CO₃ (aq) → BaCO₃ (s) + 2 NaCl (aq)

Then:

Left side: 1 barium Ba, 2 chlorine Cl, 2 sodium Na, 1 carbon C and 3 oxygen O.

Right side: 1 barium Ba, 2 chlorine Cl, 2 sodium Na, 1 carbon C and 3 oxygen O.

Finally, you have the same amount of each element on both sides.

The coefficient that must be placed against NaCl to balance this equation is 2.