A Taste of Thermodynamic’s and Reaction Rates：一味的热力学和反应速率.ppt

A Taste of Thermodynamics and Reaction Rates Nature of Energy Energy – the ability to do work or produce heat. Law of Conservation of Energy Energy can be converted from one form to another, but can not be created or destroyed. Also known as the 1 st law of Thermodynamics. Heat versus Temperature Temperature is an indication of the kinetic energy of an object. It also lets you know which way the energy will flow in relation to the surrounding objects. Heat Heat is the measure of the amount of energy. A Calorie is the metric unit of heat. It is the amount of heat needed to raise the temperature of one gram of water one degree Celsius. The SI unit is a Joule. 1 calorie = 4.184 Joules Specific Heat- the amount of heat needed to raise the temperature of one gram of that substance one degree celsius. A dietary Calorie, with a capital “C” is actually a Kilocalorie. So a 2000 Calorie diet is really a 2,000,000 calorie diet. So how do we measure Calories? Calorimeter Because we know the definition of a calorie, the mass of the water in the calorimeter and the temperature change. We can calculate the number of calories produced. q = c x m x ?T The way the book writes it. I prefer ΔH = c x m x ΔT Because you can’t really measure heat content, only the heat change. I like ΔH as change in heat. C is the specific heat of water. M is the mass of the water. ΔT is the change in temperature. See sample problem on page 524 Heat of Reaction Remember Heat of solution from last chapter? Heat of reaction is just like it, the energy change that takes place during a chemical reaction. (+) heat of rx = endothermic (-) heat of rx = exothermic Potential Energy Diagram Potential Energy Diagram II Rates of reaction How fast or how slow a reaction proceeds. This can be explained using a model called the Collision Theory Collision Theory Like two cars in a very large parking lot slowly and randomly moving around. What is the likely hood that they will