Lecture 4 Chemistry PDF

# Lecture 4 ## Ideal Gases vs. Real Gases | Feature | Ideal Gases | Real Gases | |-----------------------|--------------------|---------------------| | Actual Volume of Molecules | Negligible | Appreciable | | Attractive Force Between Molecules | Doesn't...

# Lecture 4 ## Ideal Gases vs. Real Gases | Feature | Ideal Gases | Real Gases | |-----------------------|--------------------|---------------------| | Actual Volume of Molecules | Negligible | Appreciable | | Attractive Force Between Molecules | Doesn't exist | Exist | | Molecular Collisions | Perfectly Elastic | Non-elastic | **Note:** At low pressure and high temperature, real gases are close to ideal gases. ### Compressibility Factor (Z) **Note:** In ideal gases, Z = 1. **Formula:** Z = (P * Vm)/(R * T) where P is pressure, Vm is molar volume, R is the ideal gas constant, and T is temperature. ### Van Der Waal's Equation **Formula:** (P + n²a/V²)(V-nb)=nRT. Where: - P is pressure - V is volume - n is the number of moles - R is the ideal gas constant - T is temperature - a is a specific value for each gas - b is a specific value for each gas **Note:** The pressure of a real gas is lower than an ideal gas. ## Intermolecular Forces 1. **Ion-Dipole Force:** - There is an attractive force between two or more ions. - **Example:** Na⁺, Cl⁻, H⁺, C⁻, S⁻, O⁻ 2. **Ion-Ion Interaction:** - When a cation combines with an anion, the bond between them is as strong as possible. - **Note:** Mostly this occurs in the solid state. - **Example:** Na⁺ + Cl⁻ → NaCl(s) 3. **Dipole-Dipole Interaction:** - The partial negative charge appears toward the atom that is more electronegative. - This is a special case of a dipole-dipole force. - **Examples:** H₂O, HCl **Note:** The greater the force, the stronger the intermolecular interaction, which results in a change in the state of matter. - Solid (Strongest) - Liquid - Gas (Weakest) ## Solutions - **Binary Solution:** A homogeneous mixture that consists of one phase and contains two components. - **Classification of Solutions:** - **According to amount of solute:** - **Unsaturated Solution:** A solution that accepts more solute at a given temperature. - **Saturated Solution:** A solution that contains the maximum possible amount of dissolved solute at equilibrium. - **Supersaturated Solution:** A solution that contains a greater than equilibrium amount of dissolved solute. - **According to the nature of solute:** - **Electrical conductivity of solution:** Conductivity of the solution based on the nature of the solute. **Note:** All solutions are mixtures, but not all mixtures are solutions.