Making Insoluble Salts

Question 1

What is a precipitate?

Answer 1

An insoluble salt

Question 2

Recall the solubility rules.

Answer 2

• Salts of sodium, potassium and ammonium are soluble
• Nitrates are soluble
• Chlorides are soluble (except silver chloride / lead chloride)
• Sulfates are soluble (except lead, barium and calcium sulfate)
• Carbonates are insoluble (except sodium, potassium and ammonium ones)
• Hydroxides are insoluble (except sodium, potassium and ammonium ones)

Question 3

(Exam-style question)

Answer 3

Question 4

What causes a precipitation reaction to occur?

Answer 4

Two solutions reacting to form an insoluble solid, called a precipitate, in the solution

Question 5

Describe a method used to prepare a pure, dry sample of an insoluble salt.

Answer 5

• Mix together two suitable solutions
• Once the precipitate has formed, use filtration to separate it from the solution
• Wash any remaining contaminating solution off the precipitate with distilled water
• Leave the washed precipitate aside or put it in a warm oven to dry

Question 6

Why is it important to use filtration when preparing a pure, dry sample of an insoluble salt?

Answer 6

To separate insoluble substances from liquids and solutions