Experiment Electrolytes and Non-Electrolytes 13 In this experiment, you will discover some properties of strong electrolytes, weak electrolytes, and non-electrolytes by observing the behavior of these substances in aqueous solutions. You will determine these properties using a Conductivity Probe. When the probe is placed in a solution that contains ions, and thus has the ability to conduct electricity, an electrical circuit is completed across the electrodes that are located on either side of the hole near the bottom of the probe body (see Figure 1). This results in a conductivity value that can be read by the computer. The unit of conductivity used in this experiment is the microsiemens per centimeter, or µS/cm. The size of the conductivity value depends on the ability of the aqueous solution to conduct electricity. Strong electrolytes produce large numbers of ions, which results result in result in in high conductivity values. Weak electrolytes observe low conductivity, and non-electrolytes should solution no conductivity. In this experiment, you will you to several factors that determine whether or not a their conducts, and if so, the relative magnitude of the conductivity. Thus, this simple experiment allows learn a great deal about different compounds and resulting solutions. In each part of the experiment, you will be observing a different property of electrolytes. Keep in mind that you will be encountering three types of compounds and aqueous solutions: Ionic Compounds These are usually strong electrolytes and can be expected to 100% dissociate in aqueous solution. Example:
Molecular Compounds These are usually non-electrolytes. They do not dissociate to form ions. Resulting solutions do not conduct electricity. Example:
Chemistry with Computers 13-1
The Correct Answer and Explanation is:
Correct Completion of the Experimental Summary:
In each part of the experiment, you will be observing a different property of electrolytes. Keep in mind that you will be encountering three types of compounds and aqueous solutions:
- Ionic Compounds: These are usually strong electrolytes and can be expected to 100% dissociate in aqueous solution.
Example: Sodium chloride (NaCl) - Molecular Compounds: These are usually non-electrolytes. They do not dissociate to form ions. Resulting solutions do not conduct electricity.
Example: Sucrose (C₁₂H₂₂O₁₁)
Explanation
This experiment helps students understand the behavior of electrolytes by measuring how well different substances conduct electricity in water. Conductivity is the ability of a solution to carry an electric current, which depends on the presence of free-moving charged particles called ions. The Conductivity Probe is used to measure this property. It has electrodes near the bottom that, when immersed in an ionic solution, allow current to flow, producing a measurable conductivity value expressed in microsiemens per centimeter (µS/cm).
There are three categories of substances tested in this experiment:
- Strong Electrolytes: These are substances that fully dissociate into ions in water, releasing a large number of charged particles. This leads to high conductivity readings. Most ionic compounds, like sodium chloride, fall into this category. When dissolved, NaCl separates into Na⁺ and Cl⁻ ions, which freely move in solution.
- Weak Electrolytes: These substances only partially dissociate in water, producing fewer ions. Their conductivity is much lower compared to strong electrolytes. An example would be acetic acid (CH₃COOH), which exists in equilibrium between its molecular form and its ionized form in water.
- Non-Electrolytes: These are substances that do not produce any ions when dissolved. Instead, they dissolve as whole molecules. For instance, sugar (sucrose) dissolves but does not ionize, so the solution cannot conduct electricity, resulting in a conductivity reading close to zero.
Through this experiment, students can identify the electrical behavior of substances and categorize them based on their ionic properties.
