A student has 500.0 mL of a 0.1133 M aqueous solution of BaI2 to use in an experiment. She accidentally leaves the container uncovered and comes back the next week to find only a solid residue. The mass of the residue is 28.28 g. Determine the chemical formula of this residue.

Explanation:

Hello,

In this case, by knowing the volume and the molarity of the barium iodide, is it possible to compute the residue's mass as shown below:

Nevertheless, the obtained value is lower than the obtained by 6.133 g which means that mass corresponds to water forming a hydrate. In such a way, one could know how many waters in form of hydrate remain with the residue by a trial-error procedure as shown below:

Therefore, the formula is barium iodide hexahydrate:

Best regards.

a graduated cylinder.

explanation:

the answers would be

the first one and the second one