Sample Lab Questions Investigation #5: "Alum from Aluminum Beverage Cans"

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1.

a. (1 pt) Balance this equation:
Al + KOH + H₂SO₄ + H₂O KAl(SO₄)₂12H₂O + H₂

b. (2 pts) Calculate the theoretical yield of alum that can be prepared from 2.55 g of aluminum.

2.

(3 pts) How many moles are contained in each of the following quantities of chemicals?

a.) 2.31 g of Al(OH)₃

b.) 47.32 mL of 1.4 M KOH

3.

For 2Al + 2KOH + 4H₂SO₄ + 22H₂O 2KAl(SO₄)₂12H₂O + 3H₂

a. (1 pt) Label the acid, the base, and the salt in this reaction.

b. (1 pt) Describe how to dilute concentrated H₂SO₄.

4.

(3 pts) After the aluminum had completely reacted with the KOH solution, excess strong acid was added slowly while the solution was being stirred. Describe what you visually observed. Write the formula for what you saw. Would you see the same observation if aluminum was dissolved in acid first and then treated with excess base?

5.

(2 pts) Describe the procedure for vacuum filtration.

Answers

1. (b) 44.8 g 2. (a) 0.0296 mol (b) 0.066 mol

To report any corrections, please e-mail Dr. Wendy Keeney-Kennicutt.