lab report help? [on alum crystallization]

[chaos_lover4]

PROCEDURE

1. Obtain about 1 g of aluminum foil and weigh to the nearest hundredth of a gram. Tear the foil into small pieces and place in a clean 250 mL beaker.

2. Add 25mL of 3M KOH solution to the aluminum foil in the 250 mL beaker using a 25 mL pipette. Allow reaction to proceed until all the aluminum is dissolved.

3. Flute a piece of filter paper and place in a funnel. Place the funnel into 500 mL flask. Filter the dissolved aluminum while hot to remove the carbon. Wash the beaker and the filter paper with a small amount of distilled water. Discard the filter paper and rinse the funnel. If necessary, this is a place to stop and store solution over night.

4. Obtain 35 mL of 3M H₂SO₄ in a graduated cylinder. Acidify the dissolved aluminum/KOH by adding slowly while stirring the 35 mL of 3M H₂SO₄. Use a glass rod to stir the solution. You will notice that a white precipitate forms and then dissolves in the acid. You will also notice that the solution becomes very hot as a result of mixing a strong acid with a strong base

5. If precipitate remains, filter the solution again as described above.

6. Boil the solution to a volume of about 40 to 50 mL. Allow the solution to cool slowly. This is a good stopping place.

7. Once the solution has cooled to room temperature, cover with Parafilm® or plastic wrap. You may wish to experiment with placing some of the flasks in the refrigerator. Crystals should form overnight.

8. Collect the crystals on a piece of pre-weighed filter paper and wash briefly with the 80% ethanol. Determine the percent yield relative to the expected yield.

this is what the procedure is, and here are the questions at the end.
QUESTIONS



1. Write a chemical reaction using formulas to describe this reaction. What else would we have to do in this experiment to show that that the results conform to the Law of Conservation of Mass?

2. What factors would make the yield less than 100%?

3. Why is the final filtration a wash with 80% ethanol?

4. Calculate the molar mass of alum hydrate.

5. Describe the shape of your crystals in terms of geometric shapes?

for the first question, the "balanced equation" I came up with, or rather, the equation I want to work with is Al+ KOH + H₂SO₄=KAl(SO₄)₂ . 12H₂O. It says this is an impossible equation so I want to ask if there's anything missing in this equation? or if I am doing things right? Also, under results:

2. A calculation of the percent yield based upon the amount of aluminum in the starting material. For determining the expected amount assume that 1 mol of aluminum will produce 1 mol of KAl(SO₄)₂•12H₂₀. Show your work!

I don't understand what it it's asking for, and how to go about doing it.