Investigation 4 Lab Moles
Aqueous Copper (II) Sulfate Pentahydrate
Required measurements and calculations: Copy these questions into your data book. Record measurements clearly, with units. Show all
calculations and clearly label your answers. Ask the teacher to initial your original data.
1.
2.
3.
4.
5.
6.
7.
Calculate the molar mass of hydrated copper (II) sulfate CuSO4·5H2O (include the mass of 5 water molecules in your molar mass
because these water molecules are built into the copper sulfate crystals) showing every step of your calculation.
Calculate the mass of 0.0125 moles of copper (II) sulfate CuSO4·5H2O showing every step of your calculation.
 Weigh out 0.0125 moles of copper (II) sulfate CuSO4·5H2O.
 Use a graduated cylinder to measure and place 25.0 mL of water into a plastic cup.
 Record the color changes you observe as you add the 0.0125 moles of copper (II) sulfate CuSO4·5H2O to the water in the cup,
and stir to dissolve completely.
Answer these questions about the mixture in your cup:
a) Is the mixture heterogeneous or homogeneous?
b) What is the solute in this solution?
c) What is the solvent?
d) Does your solution conduct electricity? Is this compound ionic or covalent?
Predict the appearance of the filtrate (the substances that pass through the filter) if you were to filter the solution.
 Correctly assemble a filtration apparatus, using a ring stand and ring, a plastic funnel, a beaker and a piece of filter paper.
Sketch and label the apparatus in your data book.
 Prime the filter with tap water and filter the copper (II) sulfate CuSO4 solution.
Describe the filtrate and compare to your prediction. Account for similarities and/or differences.
What substances are found in the filtrate?
Draw a model of an aqueous copper (II) sulfate solution.
Extension:
1. Grow copper (II) sulfate crystals from the filtered solution. Label the cup with your name, set it in a safe place and let the water evaporate.
2. Draw the copper (II) sulfate crystals remaining after the water evaporates. Show clearly the shape of one crystal.
3. How many copper atoms are in one mole of copper (II) sulfate? Calculate the number of copper atoms in your 25.0 mL of copper (II) sulfate
solution.
4. How many oxygen atoms are in one mole of copper (II) sulfate? Calculate the number of oxygen atoms in your 25.0 mL of copper (II) sulfate
solution.
5. How many sulfur atoms are in one mole of copper (II) sulfate? Calculate the number of sulfur atoms in your 25.0 mL of copper (II) sulfate
solution.
6. Based on the copper (II) ion (Cu2+) and the formula for copper (II) sulfate, what is the charge of the sulfate ion (SO4)?
Investigation 4 Lab Moles
Alum
Required measurements and calculations: Copy these questions into your data book. Record measurements clearly, with
units. Show all calculations and clearly label your answers. Ask the teacher to initial your original data.
1. What is the molar mass of alum (hydrated aluminum potassium sulfate AlK(SO4)2  12H2O)?
2. Put 25.0 mL of water into a plastic cup.
3. Write a brief procedure in your data book for determining how many grams of alum must be added to the
25.0 mL of water in order to make a saturated solution of alum at room temperature. You will make a
saturated solution by adding alum and stirring until no more alum will dissolve, but you must determine
the mass of alum that you add to the water in order to answer this question. How will you do this? Ask the
teacher to approve your procedure and initial your work.
4. Carry out your procedure to determine how many grams of alum must be added to the 25.0 mL of water in
order to make a saturated solution of alum at room temperature. Record the number of grams of alum
added.
5. How many moles of alum is this? (Refer back to the molar mass of alum in step 1.)
6. Is this an ionic or covalent compound? What test can you perform to determine the answer?
Extension:
1. Grow alum crystals from the saturated solution. Label the cup with your name, set it in a safe place and let the water evaporate.
2. Draw the alum crystals remaining after the water evaporates. Show clearly the shape of one crystal.
3. How many aluminum atoms are in one mole of alum? Calculate the number of aluminum atoms in your 25.0 mL of saturated alum
solution.
4. How many potassium atoms are in one mole of alum? Calculate the number of potassium atoms in your 25.0 mL of saturated alum
solution.
5. How many sulfur atoms are in one mole of alum? Calculate the number of sulfur atoms in your 25.0 mL of saturated alum solution.
6. How many oxygen atoms are in one mole of alum? Calculate the number of oxygen atoms in your 25.0 mL of saturated alum solution.