Ions: Atoms or molecules that have lost or gained one or more electrons and carry an electrical charge.
The process of dissociation occurs when compounds break apart to form ions in solution.
Electrolytes are substances that dissociate into ions when dissolved in water and conduct electricity.
Strong electrolytes fully dissociate into ions (e.g., NaCl).
Weak electrolytes only partially dissociate into ions (e.g., acetic acid).
The ability of a solution to conduct electricity is directly related to the number of ions present.
More ions -> higher conductivity.
Example: Sodium chloride
Dissociates into Na+ and Cl-, producing 2 ions.
Aluminum chloride dissolves into 4 ions (Al3+ and three Cl-), thus should have higher conductivity than NaCl.
Weak electrolytes do not fully dissociate in water and may exist in equilibrium with undissociated molecules.
Example reaction for phosphoric acid (H3PO4) indicates it produces 4 ions (3H+ + PO4 3-), but conductivity is low due to reverse reactions.
Reversible Reactions: Many chemical reactions can proceed in both forward and reverse directions.
Equilibrium state where the rate of the forward reaction equals the rate of the reverse reaction.
If the forward reaction does not proceed completely, consider the reverse reaction as significant.
Conductivity is measured to infer the degree of dissociation of electrolytes.
HCl exhibits very high conductivity due to full dissociation.
Phosphoric acid's conductivity might be lower than expected due to reverse association of ions back to the undissociated form.
The concept of ionization and its relation to conductivity is crucial for understanding the characteristics of solutions.
Review problems related to conductivity and ionization.
Focus on calculations involving molality and concentration changes in solutions.
Understand how to convert different types of concentrations (molarity to molality, etc.)
Familiarize with Henry’s Law, which relates to gas solubility, though specifics may not be emphasized on the test.
Acknowledge stress can affect performance; prioritizing classwork and comprehension alleviates pressure during testing periods.
Engagement in lessons and practical exercises enhances retention of concepts.
Teachers express empathy towards student stress, emphasizing collaborative learning and active participation as key strategies for success.
Conduct mini-experiments measuring conductivity of various electrolytes.
Understand role of impurities and composition on conductivity measurements.
Consider the implications of findings on expected chemical behavior and reactions.