HF is an acid and Ba(OH)2 is a base. They react in an acid-base neutralization reaction to give a sparingly solube salt (BaF2) that precipitates out as a solid, and water (H2O). The reaction is thus: Ba(OH)2(aq) + 2 HF(aq) => BaF2(s) + 2 H2O(l) Solution HF is an acid and Ba(OH)2 is a base. They react in an acid-base neutralization reaction to give a sparingly solube salt (BaF2) that precipitates out as a solid, and water (H2O). The reaction is thus: Ba(OH)2(aq) + 2 HF(aq) => BaF2(s) + 2 H2O(l).