GENERAL CHEMISTRY C1404 Spring 2003 Thermodynamics Electrochemistry Kinetics Professor James J Valentini Office 522 Havemeyer Phone 854 7590 Email jjv1 chem columbia edu GChem 1404 JJValentini GENERAL CHEMISTRY C1404 Spring 2003 Thermodynamics Electrochemistry Kinetics Some Course Information Homework assigned at start of each chapter Lecture notes posted on web one day after lecture Office Hours MT 12 30 1 30 GChem 1404 JJValentini THERMODYNAMICS THERMO HEAT and DYNAMICS MOTION ENERGY HEAT WORK TEMPERATURE POWER GChem 1404 JJValentini THERMODYNAMICS THERMO HEAT and DYNAMICS MOTION GChem 1404 JJValentini THERMODYNAMICS THERMO HEAT and DYNAMICS MOTION WIND TURBINE POWER GENERATION GChem 1404 JJValentini THERMODYNAMICS THERMO HEAT and DYNAMICS MOTION GChem 1404 JJValentini ENERGY SYMBOLS WORDS IN ENERGY GOLD E T V ARE IMPORTANT KINETIC ENERGY IS CONSERVED POTENTIAL DUE TO MOTION OF ATOMS MOLECULES OR OBJECTS DUE TO A FORCE BETWEEN ATOMS MOLECULES OR OBJECTS T 1 2 mv2 FOR TRANSLATIONAL MOTION MAGNETIC GRAVITATIONAL ELECTROSTATIC MAGNITUDE DEPENDS ON VELOCITY MAGNITUDE DEPENDS ON RELATIVE POSITION GChem 1404 JJValentini ENERGY ENERGY APPEARS IN MANY FORMS MOTION LIGHT SOUND WAVES AND TIDES WIND ELECTRICITY FOODS AND FUELS HEAT GChem 1404 JJValentini ENERGY ENERGY APPEARS IN MANY FORMS MOTION LIGHT HEAT SOUND GChem 1404 JJValentini ENERGY SOURCES BARREL OF OIL 5 8 x 106 Btu WORLD CONSUMPTION 7 6 x 107 barrel day 1 1 Btu 252 cal 1 Calorie 1 00 kcal 1 BARREL OF OIL 5 2 x 103 SNICKERS BARS SNICKERS CANDY BAR 280 Calories WORLD CONSUMPTION UNKNOWN GChem 1404 JJValentini ENERGY SOURCES THE ENERGY IN FOOD IS SUBSTANTIAL GChem 1404 JJValentini ENERGY ENERGY CALCULATIONS HOW MUCH ENERGY DOES IT TAKE TO WALK UP THE STEPS FROM COLLEGE WALK TO LOW LIBRARY ASSUMING THE ONLY ENERGY NEEDED IS THAT TO INCREASE THE GRAVITATIONAL POTENTIAL ENERGY OF YOUR BODY V m x g x h NOTE g 9 8 m s 2 HOW MANY TIMES DO YOU HAVE TO MAKE THIS CLIMB TO WORK OFF ONE SNICKERS BAR ANSWERS TOMORROW GChem 1404 JJValentini THERMODYNAMICS THERMO HEAT and DYNAMICS WORK STEAM ENGINE WILLIAM THOMSON BARON KELVIN OF LARGS GChem 1404 JJValentini THERMODYNAMICS THERMO HEAT and DYNAMICS WORK SCIENCE OWES MORE TO THE STEAM ENGINE THAN THE STEAM ENGINE OWES TO SCIENCE ANON GChem 1404 JJValentini THERMODYNAMICS THERMO HEAT and DYNAMICS WORK WORK w FORCE OPPOSED x DISTANCE MOVED PV WORK w P x V Force Area x Area x l WORK AGAINST GRAVITY w m x g x h WORK DONE BY SOMETHING DECREASES ITS ENERGY WORK DONE ON SOMETHING INCREASES ITS ENERGY POWER WORK PER UNIT OF TIME GChem 1404 JJValentini THERMODYNAMICS THERMO HEAT and DYNAMICS WORK BUT WHAT IS HEAT HEAT HOW DO WE MEASURE IT HEAT IS RELATED TO TEMPERATURE TEMPERATURE HOW DO WE MEASURE THAT GChem 1404 JJValentini THERMODYNAMICS THERMO HEAT and DYNAMICS WORK TEMPERATURE IS MEASURED WITH A THERMOMETER THERMOMETER WHAT IS A THERMOMETER THERMOMETER WHAT DOES A THERMOMETER MEASURE GChem 1404 JJValentini TEMPERATURE AND EQUILIBRIUM TEMPERATURE IS MEASURED WITH A THERMOMETER A THERMOMETER DETERMINES WHETHER TWO OBJECTS ARE IN THERMAL EQUILIBRIUM EQUILIBRIUM A THERMOMETER MEASURES SOME PHYSICAL PROPERTY THAT DEPENDS ON TEMPERATURE TEMPERATURE GChem 1404 JJValentini MEASURING TEMPERATURE TEMPERATURE IS MEASURED WITH A THERMOMETER A THERMOMETER NEEDS A SCALE SCALES WE USE CENTIGRADE FAHRENHEIT KELVIN KELVIN CENTIGRADE AND FAHRENHEIT SCALES DEFINED BY BOILING POINT 100C OR 212F AND FREEZING POINT OF WATER 0C OR 32F OF WATER KELVIN SCALE DEFINED BY IDEAL GAS LAW PV nRT AND HAS AN ABSOLUTE ZERO GChem 1404 JJValentini EXAMPLES OF THERMOMETERS AN ORDINARY LIQUID THERMOMETER MEASURES THE EXPANSION CONTRACTION OF A LIQUID A THERMOCOUPLE MEASURES THE TEMPERATUREDEPENDENT ELECTRICAL POTENTIAL OF THE CONTACT BETWEEN TWO DIFFERENT METALS LIQUID CRYSTALS HAVE A COLOR THAT CHANGES WITH TEMPERATURE A PYROMETER MEASURES BLACKBODY RADIATION GChem 1404 JJValentini EXAMPLES OF THERMOMETERS A PYROMETER MEASURES BLACKBODY RADIATION ALL BODIES RADIATE LIGHT DUE TO THEIR THERMAL ENERGY THE COLOR AND THE INTENSITY OF THE LIGHT REVEAL THE TEMPERATURE GChem 1404 JJValentini EXAMPLES OF THERMOMETERS BLACK BODY RADIATION IS TEMPERATURE DEPENDENT T 5 800 K T 290 K GChem 1404 JJValentini EXAMPLES OF THERMOMETERS IDEAL GAS THERMOMETER PV nRT so V nR P T GChem 1404 JJValentini HEAT VERSUS TEMPERATURE TEMPERATURE CHANGES ARE USED TO QUANTITATIVELY DEFINE HEAT PROCEDURE 1 TWO OBJECTS ARE INITIALLY NOT AT THE SAME TEMPERATURE 2 WE BRING THEM INTO CONTACT WITH ONE ANOTHER 3 WHEN THEY HAVE REACHED EQUILIBRIUM WE MEASURE THE TEMPERATURE 4 WE REPEAT THIS PROCEDURE FOR OBJECTS OF MANY DIFFERENT MATERIALS GChem 1404 JJValentini HEAT VERSUS TEMPERATURE TEMPERATURE CHANGES ARE USED TO QUANTITATIVELY DEFINE HEAT RESULTS THE TEMPERATURE CHANGE FOR EACH OBJECT DEPENDS ON THE MASS AND THE IDENTITY OF BOTH OBJECTS m1 x cs 1 x T1 m2 x cs 2 x T2 NEGATIVE SIGN BECAUSE T1 and T2 ARE OF OPPOSITE SIGN T1 Tequil T1 initial T2 Tequil T2 initial ONE OF THESE HAS TO BE NEGATIVE GChem 1404 JJValentini HEAT VERSUS TEMPERATURE TEMPERATURE CHANGES ARE USED TO QUANTITATIVELY DEFINE HEAT THE TEMPERATURE CHANGE FOR EACH OBJECT DEPENDS ON THE MASS AND THE IDENTITY OF BOTH OBJECTS m1 x cs 1 x T1 m2 x cs 2 x T2 mass cs IS THE SPECIFIC HEAT UNITS ARE Joule g 1 K 1 GChem 1404 JJValentini HEAT VERSUS TEMPERATURE HEAT IS THE FLOW OF ENERGY FROM ONE OBJECT TO ANOTHER HEAT IS GIVEN THE SYMBOL q AND IS DEFINED BY q m1 x cs 1 x T1 and q m2 x cs 2 x T2 NOW T1 and T2 HAVE OPPOSITE SIGN WHILE THE MASSES AND SPECIFIC HEATS ARE POSITIVE SO IT SEEMS WE HAVE A PROBLEM WITH THE SIGN OF q THIS WILL BE EXPLAINED IN A MOMENT GChem 1404 JJValentini MOLAR HEAT CAPACITY ANOTHER WAY TO WRITE THIS IS n1 x CP 1 x T1 n2 x CP 2 x T2 of moles CP cs x IS THE MOLAR DENSITY UNITS ARE g 1 mole 1 CP IS THE MOLAR HEAT CAPACITY AT CONSTANT PRESSURE UNITS ARE Joule mole 1 K 1 GChem 1404 JJValentini HEAT CAPACITY CALCULATIONS HOW MANY SNICKERS BARS PROVIDE ENOUGH ENERGY TO HEAT THE WATER IN A COMMON HOUSEHOLD WATER HEATER 40 GALLONS FROM 55 FAHRENHEIT TO 130 FAHRENHEIT TAKE A GUESS AS TO HOW MANY CUBIC FEET AT STP OF NATURAL GAS MOSTLY METHANE WOULD HAVE TO BE BURNED TO DO THE SAME THING ANSWERS TOMORROW GChem 1404 JJValentini