Question

You are analyzing a solid isolated from a reaction and find that its boiling point is over 1000 ∘ C . You dissolve the compound in water solution and recrystallize it to produce some solid crystals that you use to determine that the compound is a crystalline solid. Which of the following could be the identity of the unknown solid?
Check all that apply.
___Silicon dioxide SiO2
___Sodium iodide NaI
___Magnesium chloride MgCl2
___Phosphorus tribromide PBr3

Answer 1

Answer:

Sodium iodide NaI  

Magnesium chloride MgCl₂

Explanation:

Silicon dioxide SiO₂ it is not soluble in water, so it can not be recrystallized from water, it is a white solid and the boiling point is 2230 °C. This one is not the unknown solid.

Sodium iodide NaI it is soluble in water, it has a white color and the boiling point is 1304 °C . This can be the unknown solid.

Magnesium chloride MgCl₂ is soluble in water, it have a white color and the boiling point is 1,412 °C . This can be the unknown solid.

Phosphorus tribromide PBr₃ is will start a hydrolysis reaction in water, it is a colorless liquid and it has a boiling point of 173 °C. This one is not the unknown solid.