版权所有：华东理工大学物理化学教研室 9 Method: To find a starting point for a calculation in thermodynamics, it is often a good idea to go back to first principles, and to look for a way of expressing the quantity we are asked to calculate in terms of other quantities that are easier to calculate. Because the internal energy of a perfect gas arises only from the kinetic energy of its molecules, it is independent of volume; therefore, for any i s o t h e r m a l c h a n g e , i n general ΔU = q+w. Example -Calculating work, heat, and internal energy版权所有：华东理工大学物理化学教研室 9 Method: To find a starting point for a calculation in thermodynamics, it is often a good idea to go back to first principles, and to look for a way of expressing the quantity we are asked to calculate in terms of other quantities that are easier to calculate. Because the internal energy of a perfect gas arises only from the kinetic energy of its molecules, it is independent of volume; therefore, for any i s o t h e r m a l c h a n g e , i n general ΔU = q+w. Example -Calculating work, heat, and internal energy