2/27/25 CCP Chemistry Lecture (Unit 2.3, Chap 5)

Solubility Trends Overview

• Utilize a systematic approach to determine solubility of ionic compounds.

• Start with Trend #1 and proceed to lower trends until an applicable one is found.

Example Compounds

• Aluminum Oxide

  • Trend 1: Not applicable (Al is Group 3A, not 1A)

  • Trend 2: Not applicable (Oxygen is not listed)

  • Final Trend: Trend #6 applies (Oxygen has a -2 charge), predicting it to be insoluble.

• Iron Sulfide

  • Trend 1: Not applicable

  • Final Trend: Trend #6 applies (Sulfide is -2), predicting it to be insoluble.

• Titanium(IV) Chloride

  • Trend 1 to 3: Not applicable

  • Trend 4: Applies as Chloride is mentioned, predicting it as soluble.

• Nickel Hydroxide (Ni(OH)2)

  • Trend 1 to 6: Not applicable

  • Final Trend: Trend #7 (Hydroxides tend to be insoluble), hence predicted to be insoluble.

Summary of Solubility Predictions

• Only Titanium Chloride is predicted to be soluble among the compounds analyzed.

Acids and Bases

• Acids are compounds with the general formula H_a, e.g., Hydrochloric acid (HCl) and Nitric acid (HNO3).

  • Exception: H2S (Hydrogen sulfide) is an insoluble gas, deviating from typical acid behavior.

• Bases: Typically have hydroxide (e.g., Sodium Hydroxide - NaOH).

Gas Formation Reactions

Common Reactions

• Sodium Hydroxide (NaOH) with HCl: Forms Sodium Chloride (NaCl) and water; no gas produced.

• Tin (Sn) reacting with HCl: Produces Tin Chloride and hydrogen gas.

• Sulfuric Acid (H2SO4) and HCl: No gas; essentially ion swap.

Reactions Summary

• Gas formation occurs primarily in metal-acid reactions (e.g., Tin and HCl).

Redox Reactions Analysis

• Ammonium Formation: Analyzing the reaction of nitrogen gas with hydrogen.

  • Likely a Redox Reaction due to oxidation state change.

• Double Displacement reactions assumed for ionic compounds like Aluminum Chloride and Sodium Hydroxide:

  • Results in Sodium Chloride and Aluminum Hydroxide.

Oxidation Numbers and Predictions

Rules and Calculations

• Elements have oxidation state of 0, while monatomic ions follow their charge.

• For binary compounds:

  • Oxygen is typically -2, utilize the sum available to determine the unknown.

• Example: The adjustment needed for Bromate (BrO3-) producing Br as +3 through the sum rule of charges.

Example: Nitrogen Changes

• Nitrogen from a neutral state to Nitride (N^3-) is a reduction (gaining electrons).

• Oxidation: Transition from elemental nitrogen in N2 to +4 in compounds like NO2 indicates an oxidation.

Molarity Calculation

• To calculate Molarity (M):

  • Use the formula: M = moles of solute / liters of solution

  • For 50 grams of Lithium Chloride:

    • Convert grams to moles; result divided by volume gives molarity of 0.47 M.

Summary of Chapter 5

• Covered key concepts around solubility trends, acid-base reactions, redox reactions, and molarity calculations.

• Next session will delve into topics of Chapter 6.