A solid is known to be either BaCO3 or CaCO3. It is dissolved in 6 M acetic acid. A pale yellow precipitate forms when K2CrO4 solution is added. The subsequent flame test with that precipitate shows an orange-red color. Which cation is present? Briefly explain

Answer 1

solid is known to be either BaCO3 or CaCO3. It is dissolved in 6 M acetic acid. A pale yellow precipitate forms when K2CrO4 solution is added. The subsequent flame test with that precipitate shows an orange-red color. Which cation is present? Briefly explain

Answer 2

Using the results of the flame test would indicate that the precipitate is Ca2+. Although the color of the precipitate after the addition of K2CrO4 is the pale yellow of BaCrO4, that is only a superficial indication. CaCro4 is also yellow and may precipitate, particularly if the pH is high. A further test (the flame test in this case) is needed to confirm which cation is present, which in this case is Ca2+.