CHEM 1B Lecture 4: Lecture 4 Thermodynamics
Document Summary
Thermal energy transfer: energy flows as heat from hot objects to cold objects. But is conversed: suppose a block of hot metal is submerged into a beaker of cold water qmetal = mmetal x cs,metal xtmetal (joules) (mass (g)) (specific heat) (change in temp) qwaterl = mwater x cs,water xtwater. A 20 g block of al at 52 c is submerged in a 112 g of water at 17 c. Several types of work, but focus on pressure-volume (or expansion) work. Work = force x distance (w = fd) Work done by expansion against constant external pressure, pex. W = - pexv = work done by system. V = vf - vi or v = a x h (aka d = distance) A cylinder equipped with a piston expands against an external pressure of 1. 45 atm. Measuring u for chemical reactions: constant v calorimetry.
