12. Tyler is planning an experiment to test whether copper, aluminum, and zinc will react with hydrochloric acid. The unbalanced equations for the possible reactions are shown below.

 

  

     

     

 

He plans to start with 1 mol of each metal. What is the minimum number of moles of hydrochloric acid that he needs to complete each reaction once and react it completely with the metal?

Ferric Chloride 6 Hydrate FeCl6H₂O FW 270

Calcium Phosphate CaHPO₄ FW 136

Potassium Dichromate K₂Cr₂O₇ FW 294

Boric Acid H₃BO₃ FW 62

1. Describe how you would make 500 mls of each of the following:

0.3M CaHPO₄

10% H₃BO₃

5% K₂Cr₂O₇

1M FeCl6H₂O

2. You have a 10 % stock solution of K₂Cr₂O₇ . From this how would you make 200 ml of a 0.25M solution?

3. You are planning an experiment that requires you to fill 50 microfuge tubes with 0.5 ml of cells at a concentration of 5x10⁶ cells/ml. You have 50 ml of stock solution of cells at 2.3 x10⁷ cells/ml. Can you do the experiment? If no, why not. If yes, how would you prepare the cells for the experiment.

4. Describe how you would make 20 ml of a 1:300 dilution of X using only 1 and 10 ml pipettes, 12 ml capacity test tubes, and one test tube that can hold 25 ml.

5. You are planning an experiment that requires 50 ml of cells at 5x10⁵ cells/ml. Your stock contains cells at 2x10⁸ cells/ml. How would you accurately make up your working stock of cells if you only have 1 and 10 ml pipettes available to use? Can you do this experiment at all?

Experiment 2

Trial 1

a) Mass of CuSO₄·5H₂O (g) 90.000g

b) Moles of CuSO₄·5H₂O (mol) _______

c) Moles of copper in CuSO₄·5H₂O (mol) _______

d) Mass of copper in CuSO₄·5H₂O (g) _______

e) Mass of copper oxide obtained 29.267g

f) Mass of oxygen in copper oxide _______

g) Moles of oxygen in the copper oxide (mol) _______

h) Mole ratio, copper to oxygen (Cu:O) _______

i Average ratio, copper to oxygen (Cu:O) _______

j) Formula of copper oxide _______

Mass of empty beaker 85.000g

Mass of beaker and Copper (II) sulfate pentahydrate 90.000g

Mass of empty test tube 27.400g

Mass of test tube after heating and cooling 29.306g

Using your data from Trial 1, show your work for each of the following:

Moles of CuSO₄·5H₂O

Moles of copper in CuSO₄·5H₂O

Mass of copper in CuSO₄·5H₂O

Mass of oxygen in copper oxide

Moles of oxygen in the copper oxide

Mole ratio, copper to oxygen

Questions

1. How would each of the following affect your experimental determination of your copper/oxygen ratio (too high, too low, or no effect)? In each case, explain your answers.

a) You didn’t heat the solid long enough in Experiment 1.

b) The balance wasn’t properly calibrated in Experiment 1, causing all masses to be too 0.50 g too high.

c) Not all of the copper sulfate was converted to copper hydroxide in Experiment 2.

2. Write a balanced equation for the reaction occurring between copper and oxygen in Experiment 1.

3. Write a balanced equation for the reaction occurring between copper (II) sulfate and NaOH in Experiment 2.

4. Write a balanced equation for the reaction that occurred when the precipitate from Experiment 2 was heated.