Physical Chemistry Notes (PDF)

# Lecturel * **Physical chemistry** * Thermodynamics * Depend on **temperature** and **thermal changes** * Kinetics - Rate of chemical reactions * Internal energy - ΔU → kJ mol^-1 * Enthalpy of reaction - ΔH → kJ mol^-1 * Free energy - ΔG → kJ m...

# Lecturel * **Physical chemistry** * Thermodynamics * Depend on **temperature** and **thermal changes** * Kinetics - Rate of chemical reactions * Internal energy - ΔU → kJ mol^-1 * Enthalpy of reaction - ΔH → kJ mol^-1 * Free energy - ΔG → kJ mol^-1 * Entropy of reaction - ΔS → kJ mol^-1K^-1 * ΔG = ΔH - TAS * Increasing randomness increases ΔS * **Thermochemistry** * Is a part of Physical Chemistry which concerns the study of thermal change. * It deals with physical and chemical transformation and aims to quantitively determine the heat absorbed or released. * Aims to develop ways to calculate the thermal changes so that the reaction can continue to occur. * It has to be known that the heat released or observed is absorbed. * **Thermodynamics** * Is a part of Physical chemistry which is used to study heat transfer. * Heat is a form of energy. * The study of quantum relations between heat and other energies predict whether the chemical reactions occur or not. * **Types of thermodynamics** * **Classical Thermodynamics** * Studies thermodynamics parameters in **macro scales** * **Statistical Thermodynamics** * Studies thermodynamics parameters in **micro scales** # Some Definitions of Thermodynamics * **System** * A continuous or separate part of the universe consisting of matter or substances involved in chemical reactions or physical changes. * They can be real or imagined and all remains outside of the system are called "surrounding". * They are capable of being separated from the system or allowing heat to be exchanged between the system and the surrounding. * **Types of systems according to:** * **Nature of the system** * **Open system** * The system in which energy and materials exchange between the system and the surrounding * **Closed system** * The system which the exchange of energy happens between the system and the surrounding. * **Isolated System** * The system in which energy and material do not exchange between the system and the surrounding. * **Nature of the phase** * **Homogeneous** * The system in which the chemical reactions happen when all the components of the system are present in one phase or the same phase. * **Heterogeneous** * The system in which the chemical reactions happen when all the components of the system are present in two or more phases. * **Example** * **Homogeneous** * CH₃COOH_(l)+C₂H₅OH_(l)→CH₃COOC₂H_5(l)+H₂O_(l) * H_2(g)+I_2(g)→2HI_(g) * PCl_5(g)→PCl_3(g)+Cl_2(g) * **Heterogeneous** * CaCO_3(s)→CaO_(s)+CO_2(g) * C_(s)+O_2(g)→CO_2(g) * **State** * It does not refer to the state of matter (solid-liquid-gas) but refers to the state of functions such as * ΔU - Internal energy * ΔH - Enthalpy * ΔG - Free energy * ΔS - Entropy * All stated function parameters change under different conditions. * We can calculate the **volume, pressure, and temperature** from general laws of gases. * PV = nRT * PV = RT * P = (RT)/V * V = (RT)/P * T = (PV)/R * **Phase**: State of material solid, liquid, gas * **Notes:** * The melting point of ice is 32° F. * The boiling point of water is 212° F. * 1° C = 1.8° F. * F = (5/9)*C + 32 * C = (9/5)*(F-32) * K = C + 273 * 1 Cal = 4.184 J * Q = MCΔT # Lecture 2 * **Units of used in thermodynamics** * **Force (F):** * The tendency to change from static to motion * The ability to change from silent to movement state * Measured by Newton N = kg.m.s^-2 * **Capacity (C):** * The rate of working in terms of time * Occurs work in time period * Measured by Watt - W =J/s * **Energy (E):** * The ability to do work * Measured by Joule * J = kg.m².s^-2 = N.m = 10⁷erg * **Joule:** * The energy needed to move 1 kg of materials at a speed of 1 m/s for a distance of 1m. * **Heat capacity:** * The amount of heat it takes to lift 1 g of substance to 1°C. * **Internal energy:** * Summation of all energies presents in the chemical reactions. * Unit is J.mol * ΔU = U₂ - U₁ * U_Reactant - U_Products * U_Final - U₁ * **Work and mechanism work** * Thermal exchange of heat between the system and surroundings. * The effect of force on the areas called mechanical work. * W = FΔL * + value = expansion * - value = the negative charge to the pressure * P = F/A * F = PA * W = FΔL = PAΔL = PΔV * W = PΔV = P(V₂ - V₁) * **First law of thermodynamics** * Studies the relation between change in internal energy and the work done. * Energy doesn't create nor produce, but it can move from one place to another or transfer from one to another. * U_f + q = U_i + q + W * ΔU = q + w * U_f = U_i + q + W * ΔU = q - PΔV * ΔU = change in internal energy → kJ.mol^-1 * q = heat of energy → kJ.mol^-1 * P = Pressure → atm * ΔV = change in volume → L.mL * **Cyclic processes** * **Isothermal processes:** * ΔU = q+w * 0 = q + w * q = -PΔV * ΔU = q - PΔV * 0 = q -PΔV * q = PΔV * **Adiabatic processes:** * q = 0 * ΔU = 0-PΔV * ΔU = q + w * ΔU = 0+w * ΔU = w * **Relation between internal energy and enthalpy** * **At constant volume** * ΔU = q + w = q - PΔV = q - P (V₂-V₁) = q - 0 = q =0 * ΔU = w * q = heat of energy at constant volume * **At constant pressure** * ΔU = q + w = q - PΔV * ΔU = U_p-U_R * ΔV = V_p-V_R * U_p-U_R = q-P(V_p-V_R) * U_p-U_R = q_p-PV_p+PV_R * U_p + PV_p = q_p + PV_R - U_R * H_p = V_p + H_R * q_p = H_p - H_R * q_p = ΔH * ΔH = ΔU + PΔV * ΔH = ΔU + ΔnRT * **Ideal gas** * ΔH = ΔU + PΔV * PV = nRT * PΔV = nRΔT * P(V_R-V_P) = PΔV = ΔnRT * ΔH = ΔU + ΔnRT