《化学专业英语》课件chapter6

单击此处编辑母版标题样式,单击此处编辑母版文本样式,第二级,第三级,第四级,第五级,*,Chapter 6,Thermochemistry,6.1 Energy,Energy in Chemical Reactions,breaking,chemical bond requires energy,formation,of chemical bond release energy,Thermodynamics,system,:,the area of study,surroundings,:,the rest of the universe outside the area of study,exothermic process : releasing heat from a system,endothermic process : absorbing heat from surroundings,Raising the temperature,Phase change,Chemical reaction,Increase of the Internal energy,3.Internal Energy,4. Energy, Heat, and Work,First law of thermodynamics,Enthalpy: H = u +,pV,6.2 Heats of Reaction and Other Enthalpy Changes,Heats of Reaction: at constant pressure: H,Exothermic processes : H is negative Endothermic processes: H is positive,2. Standard State and Standard Enthalpy Changes, Heats of Formation, and Heats of Combustion,Standard state of,sustance,: at 1atm and a specified temperature (usually 298K),Standard enthalpy changes:,Heat of formation of one mole substance by combination of its elements in their standard states,Standard enthalpy of formation,:,Standard enthalpy of combustion,Heat of reaction of one mole of substance with oxygen in standard state,3. Finding Enthalpy Changes and Heats of Reaction from Standard Heats of Formation,N.B.,Coefficient,of products and reactants of the reaction equation,4. Heats of Changes of state,6.3 Measuring Heat,1. Heat Capacity,C,: heat needed to raise the temperature of a mount of substance by 1K,Molar heat capacity,: heat needed to raise the temperature of one,mole of substance by 1K,e.g.,A calorimeter with a Cp of 60 J/K was used to find the heat flow associated,with the dissolution of 24 g of,NaCl,in 176g of water. The observed T was -1.6K.,The specific heat of the resulting,NaCl,solution is 3.64,J(Kg,). What is the heat flow for this process?,