When Ba(OH)₂ is completely neutralized with HCL, which of the following is the mole ratio of Ba(OH)₂ to HCl in this reaction? A) one to four, B) one to two, C) one to one, D) two to one, or E) four to one.
To solve this problem, we need to create a balanced chemical equation for the reaction between Ba(OH)₂, or barium hydroxide, and HCl, or hydrochloric acid. Ba(OH)₂ and HCl are a reactants for this reaction. This is a neutralization reaction because barium hydroxide is a base and HCl is an acid. When an acid reacts with a base, the products are water and a salt, which in this case will be BaCl₂ or barium chloride. Now that we’ve determined the products and the reactants for this reaction, we just need to balance our equation.
Right now, before balancing, we have one barium and both the products and the reactants. We have two oxygens in the reactants but only one oxygen in the products. We have three hydrogens in the reactants and two hydrogens in the products. And we have one chlorine in the reactant but two chlorines in the products. Since we have two chlorines in the products from BaCl₂ but our bariums are already balanced, let’s try adjusting the chlorine by putting a two in front of the HCl. Now, we have four hydrogens and two chlorines in the reactants and two hydrogens and two chlorines in the products.
Now, the only elements that aren’t balanced are the oxygen and hydrogen. We have less of both in the products. So we can fix that by putting a two in front of the water. Now, we have the same number of all of our elements on both sides of our equation. The question asked us to determine the mole ratio of Ba(OH)₂ to HCl. As we can see in our chemical equation, for every one mole of barium hydroxide, we have two moles of HCl. This matches answer choice B, the mole ratio of Ba(OH)₂ to HCl is one to two.