Question

Balance: ${H_2}{C_2}{O_4}(aq) + {K_2}Cr{O_4}(aq) + HCl(aq) \to CrC{l_3}(aq) + KCl(aq) + {H_2}O(l) + C{O_2}(g)$

Answer 1

The addition of stoichiometric coefficients to the reactants and products is required to balance chemical equations. This is crucial because a chemical equation must follow the laws of conservation of mass and constant proportions, which means that the reactant and product sides of the equation must have the same number of atoms of each element.

Complete Step By Step Answer:
${H_2}{C_2}{O_4}(aq) + {K_2}Cr{O_4}(aq) + HCl(aq) \to CrC{l_3}(aq) + KCl(aq) + {H_2}O(l) + C{O_2}(g)$
In the above equation, we see that the oxidation number of $C$ increases from $+ 3$ to $+ 4$ and the oxidation number of $Cr$ decreases from $+ 6$ to $+ 3$
We need $3$ atoms of $C$ for every $1$ atom of $Cr$ or $6$ atoms of $C$ for every $2$ atoms of $Cr$ .
Hence, balancing the above equation we get,
$3{H_2}{C_2}{O_4} + 2{K_2}Cr{O_4} + 10HCl \to 2CrC{l_3} + 4KCl + 8{H_2}O + 6C{O_2}$

Additional Information:
Stoichiometric coefficients are now applied to compounds that contain an element with a different number of atoms on the reactant and product sides.
The number of atoms on either side must be balanced by the coefficient.
The stoichiometric coefficients are usually assigned last to hydrogen and oxygen atoms.
It's important to remember that the stoichiometric coefficient must be multiplied by the total number of atoms of that element present in 1 molecule of the species to get the number of atoms in that species.

Note:
The balancing of a chemical equation is governed by the law of conservation of mass. This law states that in a chemical reaction, mass cannot be generated or destroyed, and that the total mass of the elements or molecules present on the reactant side should match the total mass of elements or molecules present on the product side.