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JoVE Lab Manual
Lab: Chemistry

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Learning Objectives

At the end of this lab, students should know...

What is solubility?

Solubility describes how much solute can dissolve in a solvent. This depends on the dissolution process between the solute and the solvent, so a solute will have different solubilities in different solvents.

What can affect solubility?

Solubility is affected by the temperature of the system. You should always check what temperature is associated with a solubility value. Solubility usually increases with temperature, but there are exceptions.

What is a simple way to predict solubility?

The phrase “like dissolves like” reminds us that polar solutes typically have good solubility in polar solvents and poor solubility in nonpolar solvents, while nonpolar solutes typically have good solubility in nonpolar solvents and poor solubility in polar solvents.

What is a saturated solution?

A saturated solution contains the maximum amount of dissolved solute given the volume and temperature of the solvent. The dissolution and precipitation of the solute are in equilibrium, so the overall rates of dissolution and precipitation are the same.

What can the changes in entropy, enthalpy, and Gibbs energy tell us about a solution?

The change in entropy of a solution tells us whether the dissolution reaction is completely reversible. The change in enthalpy of a solution tells us whether heat was absorbed or released during dissolution. The change in Gibbs energy tells us whether the dissolution was spontaneous or whether the system required additional energy to dissolve the solute.

List of Materials

  • 0.1% bromocresol green
    10 mL
  • 12.1 M hydrochloric acid
    30 mL
  • Ring stand
  • Burette clamp
  • 50-mL glass burette
  • Thermometer clamp
  • Digital thermometer
  • Glass thermometer
  • Long-stem funnel
  • 5-mL volumetric pipette
  • 10-mL capacity pipetter
  • 50-mL graduated cylinder
  • 250-mL Erlenmeyer flask
  • 400-mL beakers
  • 150-mL beaker
  • Hot plate
  • Magnetic stir bar
  • Dropper bottles
  • Lab spatulas
  • Weighing boats
  • 150-mL beaker
  • 20-mL volumetric pipette
  • 500-mL volumetric flask
  • 500-mL polyethylene bottle with a cap
  • Paper towels
    Dependent on lab size
  • Deionized water
    Dependent on lab size
  • Balance (minimum 1)
    Dependent on lab size
  • Sodium tetraborate decahydrate (Borax)
    100 g

Lab Prep

Source: Smaa Koraym at Johns Hopkins University, MD, USA

  1. Lab Preparation for Determining the Solubility of Borax

    Here, we show the laboratory preparation for 10 students working in pairs, with some excess. Please adjust quantities as needed.

    • Assign each of the lab groups a temperature of either 10, 20, 30, 40, or 50 °C. Note: There can be duplicates for larger class sizes.
    • Place a stock bottle of borax, weighing boats, and a spatula at each weigh station.
    • Prepare one dropper bottle containing 1-2 mL of 0.1% bromocresol green indicator for each lab group.
    • Prepare a 0.5 M solution of HCl. For 500 mL, use a volumetric pipette to transfer 20 mL to a 500-mL volumetric flask. Dilute the solution to the 500-mL mark with deionized water, and mix the solution on a stir plate until it appears homogeneous. Transfer the solution to a bottle and store it in an appropriate location until the lab session.
    • Set out the following glassware for each student group (we suggest that students work in pairs):
       1    Ring stand
       1    Burette clamp
       1    50-mL glass burette
       1    Thermometer clamp
       1    Digital thermometer
       1    Glass thermometer
       1    Long-stem funnel
       1    5-mL volumetric pipette
       1    10-mL capacity pipetter
       1    50-mL graduated cylinder
       5    250-mL Erlenmeyer flasks
       2    400-mL beakers
       1    150-mL beaker
       1    Stirring hotplate
       1    Stir bar

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