Question

How do you write an equation for the reaction between sodium chloride, sulfur dioxide gas, steam, and oxygen to give sodium sulfate and hydrogen chloride gas?

Answer 1

`4NaCl_((s)) + SO_(2(g)) + 2H_2O_((l)) + 2O_(2(g)) -> 2Na_2SO_(4(aq)) + 4HCl_((g))`

Explanation:

When you balance, start of with the most complicated molecules, and leave the simpler molecules to last. In this case, we want to balance `Na_2SO_(4(aq)), NaCl_((s)) and HCl_((g))` first.

`2NaCl_((s)) + SO_(2(g)) + H_2O_((l)) + O_(2(g)) -> Na_2SO_(4(aq)) + 2HCl_((g))`

We need two sodiums on the reactants side, so we place a two in front of sodium chloride. Then we need two chlorines as we just added two to sodium chloride, so we place a two in front of hydrogen chloride.

Now count your elements and see what's missing. We have 1 sulfur on both sides, 2 hydrogens, but we have 5 oxygens on the reactants side and only 4 on the products. Since the number of oxygens on the products can only be even, as it is in `SO_4`, we have to make the number of oxygens on the reactants even and then rebalance. The molecule that's making the number of oxygens odd is water, so we add a 2 to make it even and rebalance everything, getting:

`4NaCl_((s)) + SO_(2(g)) + 2H_2O_((l)) + 2O_(2(g)) -> 2Na_2SO_(4(aq)) + 4HCl_((g))`