Question

When the following equation is balanced with the smallest integral coefficients, the coefficient of the HCl(g) is ______.
H₂O(l) + SO₂Cl₂(l) → HCl(g) + SO₃(g)

Answer 1

For balancing equations, different methods are possible (in this case, balancing by inspection). The balancing equations is done in order to follow the law of conservation of mass (the mass of a system should remain constant over time).

Balancing by inspection consists that every atom present in the equation have the same proportion in both the reactants and the products.

In the reactants we have:                  H2O = 2 hydrogens and 1 oxygen.
                                                          SO2Cl2 = 1 sulfur, 2 oxygens and 2 chlorine.

                                                          TOTAL Reactants = 2 hydrogens, 3 oxygen, 1 sulfur and 2 chlorine.

In the products we have:                   HCl = 1 hydrogen and 1 chlorine.
                                                          SO3 = 1sulfur and 3 oxygens.

                                                          TOTAL Products = 1hydrogen, 3 oxygens, 1 sulfur and 1 chlorine.

To balance equations, coefficients are added only to the compounds that need to be balanced, but the subscripts are not changed.

We begin adding coefficients, starting with low numbers (1, 2, 3, and so on) to get balanced equation. At the end we count each atom (reactants and products) to know that we have the same number in each side.