CHM 2104 Chemical Thermodynamics PDF

CHM 2104 Chemical Thermodynamics Hour 1: Introduction to Chemical Thermodynamics and its importance/relevance in the Sciences Hour 2: Basic ideas of systems, states, changes, equations of state. Revision of ideal gases  Analytical Chemistry...

CHM 2104 Chemical Thermodynamics Hour 1: Introduction to Chemical Thermodynamics and its importance/relevance in the Sciences Hour 2: Basic ideas of systems, states, changes, equations of state. Revision of ideal gases  Analytical Chemistry Biological Chemistry Chemistry Inorganic Chemistry The study of matter and its transformations Organic Chemistry Physical Chemistry 2  Thermodynamics Physical Chemical kinetics Chemistry The study of the physics (physical Quantum mechanics principles) that underpin chemistry It examines matter on a molecular Electrochemistry and atomic level and explores how and why chemical reactions occur Nuclear Chemistry 3 What is Chemical Thermodynamics? ▪ Thermodynamics is the study of ▪ Why would we be interested in the the transformations of energy and energy transformations of systems? the relations between energy the bulk properties of matter. ▪ What do you know about equilibrium? ▪ “The purpose of thermodynamics ▪ Why would we be interested in is to predict the equilibrium equilibrium? composition of a system from the properties of its components.” – Stephen Lower ▪ How might knowing the equilibrium composition of a system be useful? 4 Why is Chemical Thermodynamics important? ▪ Chemical thermodynamics is a part of everyone’s daily life ▪ Cooking food ▪ Chemical manufacturing ▪ Power plants ▪ Engines ▪ Heat pumps ▪ Refrigerators, Air conditioners Image source: Harabi et al (2024) Adsorption of pesticides on ▪ Distillation activated carbons from peach stones. Processes 12(1) ▪ Separations https://doi.org/10.3390/pr12010238 ▪ Explosions 5 Basic ideas: Systems, states of matter ▪ Types of systems ▪ Open Surroundings ▪ Closed Region outside ▪ Isolated System the system The part of ▪ Physical states of matter: the world we ▪ Solid are studying ▪ Liquid ▪ Gas Universe 6 Thermodynamic States of gases ▪ Thermodynamic state its condition at a specific time as defined by a set of thermodynamic variables ▪ Set of variables to completely define the system: ▪ Pressure (p), ▪ Volume (V), ▪ temperature (T) and ▪ number of moles (n) ▪ These variables are related. The relationship is called the equation of state and has general form: ▪ p = f (T, V, n) ▪ The equation of state for an ideal gas (perfect gas): ▪ pV = nRT where R is the ideal gas constant = 8.314 JK-1mol-1 7 Pressure ▪ Pressure: force divided by area 𝑭 ▪ 𝑷= 𝑨 ▪ F is force, measured in Newtons (N) and A is area (m2) ▪ The SI unit for pressure is the Pascal (Pa) ▪ 1 Pa = 1Nm-2 = 1 kg m-1s-2 ▪ Other units of pressure: bar, atmosphere, Torricelli, mmHg, pound per square inch 8 Temperature ▪ Temperature is the property of an object which determines in which direction the energy will flow when the object is in contact with another object. ▪ A measure of the average kinetic energy of a body; sensed as hotness or coldness ▪ Temperature is measured on the Celsius and Kelvin scales. T(K) = T(oC) + 273.15 ▪ Thermal boundaries: Diathermic vs Adiabatic ▪ Zeroth Law of Thermodynamics: If two bodies A and B are in thermal equilibrium with a third body C, then they are in thermal equilibrium with each other. 9 Amount of substance ▪ One mole of substance = number of particles of substance as there are in 12g of 12C. ▪ This number is Avogadro’s number = 6.022 x 1023 ▪ Molar mass = mass of 1 mol of substance ▪ Molar mass (M) = mass (m)/number of moles (n) ▪ Unit is gmol-1 10 Boyle’s law: p  1/V (at constant T) ▪ At constant temperature, the pressure of a fixed amount of gas is inversely proportional to its volume 1 ▪ Also 𝑉 ∝ 𝑝 ▪ Each line is an isotherm (a line of constant temperature) ▪ Only valid at low pressures 11 Boyle’s law cont’d ▪ Pressure is directly proportional to 1/V 12 Charles law: V  T (at constant P) ▪ At constant pressure, the volume of a fixed amount of gas is directly proportional to temperature 13  Ideal gas law, aka the Perfect gas law Avogadro’s principle Putting it all together ▪ At a given temperature and pressure, equal volumes of gas contain equal numbers of particles ▪V  n ▪ Replacing proportionality sign 14