Work in groups on these problems. You should try to answer the questions without referring to your textbook. If you get stuck, try asking another group for help.
Workshop: Ions in Solution
1) For each of the following compounds, (a) write the formula and (b) classify it as either a strong or a weak electrolyte or a non-electrolyte.
|Compound||Formula||Strong, Weak or Non-Electrolyte|
2) For each of the following, a description of a solution is provided. (a) Calculate the molarity of the solution, and then (b) write the formulas of all of the species present in the solution. Underline the major dissolved species. The first line is completed as an example.
|Solution||Solution's Molarity||Concentration of Solute Species in Solution|
|0.1000 mole of NaCl in 1.000 L of aqueous solution||0.1000 M||0.1000 M Na+(aq), 0.1000 M Cl- (aq)|
|1.250 g of NaCl in 1.500 L of aqueous solution|
|1.325 moles of acetic acid (CH3COOH) in 1.300 L of aqueous solution [Assume that 5% of acetic acid dissociates in water.]|
|0.235 grams of NaOH in 100.0 mL of aqueous solution|
3) a) Draw a particulate-level sketch of a potassium dihydrogen phosphate (KDP) solution that was prepared from 2 KDP molecules and 4 H2O molecules.
b) Draw a particulate level sketch of what remains after the water has been removed.
4) Brainstorm to come up with a list of methods you could use to speed up the process of dissolving sugar in water. When you have completed the list, choose the three best methods from your list. Provide in words an explanation at the particulate-level of why each method speeds up the dissolving process.
5) Describe two methods of recovering the sugar in solid form from the solution.
6) A solution is made by dissolving 1.0 g of potassium dihydrogen phosphate in 1.0 L of water. Assume that the volume of the resulting solution is 1.0 L and that the density of water and the resulting solution is 1.0 g/mL. Determine the molarity of the solution.
7) A student is instructed to prepare 3.00 L of a 0.100 M solution of copper(II) sulfate. She goes to the stockroom and finds a 100 g bottle of the anhydrous salt, which cost $14.00 and a 500 mL bottle of a 1 M solution, which cost $12.50. Which source provides the most economical way of making the solution? Would it be cheaper to use CuSO4 . 5H2O which costs $37.50 / 500 g. Show your calculations.
8) Your group works in a chemical research laboratory. The following volumetric flasks are available: 10 mL, 25mL, 50 mL, 100 mL, 200 mL, 250 mL, 500 mL, 1000 mL, and 2000 mL. You also have access to all of the ionic compounds needed and a source of distilled, deionized water. Carefully and precisely explain how you would make each of the following solutions:
1.00 L of a 0.70 M solution of sodium chloride (table salt), NaCl.
0.50 L of a 2.5% w/w solution of sucrose (table sugar), C12H22O11.
0.10 L of a 10.0% v/v solution of ethanol, C2H5OH.
0.40 L of a 5.0% w/v solution of ammonium phosphate, (NH4)3PO4.