- WELCOME TO PART THREE OF THE VIDEO TUTORIAL SERIES
ON CHEMICAL REACTIONS.
THIS SEGMENT WILL FOCUS ON THERMODYNAMICS.
THE HEAT OF REACTIONS.
LET'S GET STARTED. ALL RIGHT.
SO, WHEN THINK ABOUT THE WORD THERMODYNAMICS, THINK HEAT.
AND WE CAN REMEMBER THAT HEAT IS SYMBOLIZED WITH THE SYMBOL Q.
AND THIS IS...
WE'RE GOING TO RELATE THIS HEAT
AS IT CONNECTS TO REACTION ENERGIES.
SO, RIGHT, ENERGY IS THE CAPACITY TO DO WORK
OR TRANSFER HEAT.
SO, IN THE CONTEXT OF CHEMICAL REACTIONS,
WE'RE REALLY FOCUSING ON THE HEAT TRANSFER.
DOWN THE ROAD, WE WILL BE LOOKING AT THIS
AS IT'S RELATED TO BIOCHEMISTRY AND THE FIELD OF BIOENERGETICS.
WE WILL SEE WHERE THE TRANSFER OF ENERGY OF REACTIONS
IN OUR CELLS.
AND FOR OUR CLASS, MOSTLY LIKE, HOW THE FOOD THAT WE EAT
BECOMES A SOURCE OF ENERGY WITHIN OUR BODY.
SO, TO BE ABLE TO TALK ABOUT ENERGY,
WE SHOULD GO OVER UNITS OF ENERGY.
AND IT'S INTERESTING.
SCIENCE AND NUTRITION HAVE TAKEN A DIFFERENT APPROACH.
SO, THE SCIENCE DEFINITION OF A CALORIE
IS THE AMOUNT OF HEAT ENERGY REQUIRED
TO RAISE THE TEMPERATURE OF ONE GRAM OF WATER BY ONE DEGREE C.
SO THIS IS AN EXAMPLE WHERE WE HAVE TO PAY ATTENTION
TO THE CASE, ALL RIGHT.
SO, IN SCIENCE, IT'S A LOWER CASE C.
ALL RIGHT, SO HOWEVER FOR FOOD, FOR NUTRITION,
NUTRITION USES UPPER CASE C.
SO, IF WE PUT AN UPPER CASE C HERE FOR CALORIE,
THEN THIS IS TELLING US, UPPER CASE,
THIS WOULD BE IN NUTRITION OR FOOD, ALL RIGHT?
SO NUTRITION USES THE UPPER CASE.
OH, YEAH, CALORIES.
SO, THERE IS A CONNECTION BETWEEN THE SCIENCE
AND NUTRITION DEFINITIONS OF CALORIE.
SO, ONE NUTRITION CALORIE WITH AN UPPER CASE C,
IS EQUAL TO A THOUSAND SCIENCE CALORIES.
AND THEN IN SCIENCE-- WELL, WE'LL KEEP GOING THERE.
AND SO NOW, LET'S BRING--LET'S LINK THIS TO WHAT WE UNDERSTAND
ABOUT METRIC PREFIXES, RIGHT,
SO WHAT'S ANOTHER WAY TO WRITE A THOUSAND CALORIES, RIGHT,
THAT WOULD BE ONE KCAL.
ALL RIGHT.
WITHIN SCIENCE, WHERE THERE IS ANOTHER UNIT SYSTEM
THAT WE CAN ALSO USE AND SO IN THE SCIENCE WORLD,
ONE CALORIE IS EQUAL TO 4.184 JOULES, ALL RIGHT.
AND SO, THAT UPPER CASE J IS SYMBOLIZING THE ENERGY UNIT
OF JOULE.
SO THOSE ARE THE THREE ENERGY UNITS
THAT WE WILL BE USING IN THIS COURSE.
SO, BEFORE WE GET TO REACTIONS,
LET'S MAKE SURE WE UNDERSTAND THESE ENERGY UNITS.
SO, LET'S SAY FOR EXAMPLE THAT WE WANT TO EAT A MUFFIN,
AND THE LABEL TELLS US THAT THERE ARE 350 CALORIES, RIGHT,
SO WE NOTICE, THESE ARE THE NUTRITION CALORIES
OR THE FOOD CALORIES.
LET'S DO A SIMPLE CALCULATION TO GET THIS INTO JOULE ENERGY.
ALL RIGHT. SO WE START WITH WHAT WE KNOW.
WE KNOW WE HAVE A MUFFIN WITH 350 NUTRITION CALORIES.
NOW, WE DON'T HAVE A DIRECT LINK
BETWEEN NUTRITION CALORIES AND JOULES.
SO WE'RE GOING TO GO TO THE SCIENCE CALORIES, ALL RIGHT?
SO, FOR EVERY NUTRITION CALORIE WITH THE UPPER CASE C,
WE WILL HAVE A THOUSAND SCIENCE CALORIES WITH THE LOWER CASE C.
SO WHEN WE'RE--SO WE--WHEN YOU'RE DOING QUIZZES AND TESTS,
YOU HAVE TO MAKE SURE THAT YOU'RE VERY CAREFUL
WITH YOUR PENMANSHIP
SO THAT YOU COMMUNICATE YOUR KNOWLEDGE TO YOUR PROFESSOR,
ALL RIGHT?
SO NOW WE HAVE CONVERTED OUT OF NUTRITION CALORIES
AND INTO FOOD CALORIES,
AND SO WE CAN BRING IN NOW OUR CALORIE TO JOULE CONVERSION
THAT FOR EVERY SCIENCE CALORIE,
THAT WOULD CORRESPOND TO 4.184 JOULE UNITS, ALL RIGHT.
SO, NOW WE WOULD PUNCH THIS INTO OUR CALCULATOR
AND THE CALCULATOR IS GOING TO SPIT OUT A VERY LARGE NUMBER.
NOW, WE KNOW WHY THE FOOD INDUSTRY DOESN'T USE JOULES,
RIGHT?
NOBODY WOULD WANT TO EAT ANYTHING.
THE CALORIES ARE OVERWHELMING.
AND THIS IS A GOOD OPPORTUNITY TO OUR REVIEW OF SIGFIGS, RIGHT?
SO HOW--WHAT SHOULD WE REPORT HERE, RIGHT,
WE HAVE TWO SIGFIGS IN OUR LABEL OF OUR MUFFIN.
THIS IS A DEFINED CONVERSION, INFINITE SIGFIGS,
WRITE IT'S EXACT
AND THEN WE HAVE A UNIT CONVERSION
BETWEEN CALORIES AND JOULES FOR SIGFIGS.
SO, IN REPORTING THIS FINAL ANSWER,
WE WOULD ONLY WANT TO REPORT TWO SIGFIGS.
SO REMEMBER THAT THE SIGFIGS ARE TELLING US
THAT WE KNOW THE ONE FOR CERTAIN
AND THEN WE'RE GUESSING HERE, RIGHT?
THIS IS OUR UNCERTAINTY.
SO WE LOOK TO THE RIGHT AND WE WOULD ROUND UP.
SO, IN REPORTING OUR FINAL ANSWER ON THIS MUFFIN,
WE WOULD SAY THAT THE MUFFIN HAS 1.5 MILLION JOULES OF ENERGY.
WOW. OKAY.
AND IF WE WANTED TO WRITE THIS IN SCIENTIFIC NOTATION,
WE WOULD WRITE IT AS 1.5 X 10 TO THE 6TH.
AND EITHER ANSWER IS FINE. OKAY.
SO NOW THAT WE'RE COMFORTABLE
WITH THE UNITS OF HEAT AND ENERGY,
LET'S CONNECT THOSE TWO REACTIONS.
SO, WHEN WE TALK ABOUT HEAT ENERGY
IN RELATIONSHIP TO REACTIONS,
WE'VE INTRODUCED A NEW TERM, ENTHALPY.
ENTHALPY IS SYMBOLIZED WITH THE LETTER H.
AND BECAUSE REACTIONS ARE ABOUT CHANGE, RIGHT,
OR DELTA WOULD BE THE CHANGE, RIGHT, IN HEAT.
AND WHEN WE'RE TALKING ABOUT HEAT WITH RESPECT TO REACTIONS,
WE USE THE TERM ENTHALPY.
SO LINGUISTICALLY, THERE'S A LITTLE BIT OF VOCABULARY THERE,
OKAY?
SO THE FIRST LAW OF THERMODYNAMICS,
CONSERVATION OF ENERGY,
SPECIFICALLY HEAT SAYS THAT IT REFERS TO ALL FORMS OF ENERGY.
ENERGY CAN NEITHER BE CREATED NOR DESTROYED.
AND SO THIS IS WHERE WE'RE GOING TO CONNECT THE ENERGY, RIGHT,
THAT IS HELD IN THE CHEMICAL BONDS.
WE'RE GOING TO RELATE THAT TO THE HEAT ABSORBED OR RELEASED
IN A CHEMICAL REACTION.
OKAY. SO THAT'S REALLY THE HEART OF THIS TUTORIAL.
SO THE DELTA H IS THE HEAT OF THE REACTION.
IT DESCRIBES THE HEAT GIVEN OFF OR ABSORBED.
AND WE DESCRIBED THAT AS THE REACTION ENTHALPY. OKAY.
SO, WE'VE ALREADY NOTICED--
WELL, WAIT, THE HEAT CAN BE GIVEN OFF OR ABSORBED.
SO WE'VE GOT A FEW MORE TERMS TO LEARN HERE,
EXOTHERMIC AND ENDOTHERMIC REACTIONS.
THESE ARE THE TERMS WE USE TO TELL EVERYBODY
WHICH WAY THE HEAT FLOWS, RIGHT?
NOT ALL REACTIONS RELEASE HEAT.
SOME REACTIONS NEED HEAT TO OCCUR.
SO WE HAVE TWO DIFFERENT TERMS TO DESCRIBE THESE REACTIONS.
WITH AN EXOTHERMIC REACTION, WRITE EXO, EXITS, RIGHT?
THE REACTION GIVES OFF HEAT, HEAT EXITS THE REACTION. RIGHT?
SO THAT--WHAT IS THAT TELLING US ENERGETICALLY ABOUT THE PRODUCTS
AND THE REACTANTS,
THAT'S TELLING US THAT THE PRODUCTS ARE LOWER
IN POTENTIAL ENERGY THAN THE REACTANTS.
SO WE'VE TALKED ABOUT IT LINGUISTICALLY.
LET'S LOOK AT IT IN TERMS OF A GRAPH, ALL RIGHT?
SO THIS WILL BE THE ENERGY ON THE Y-AXIS INCREASING
AS WE GO UP THE SCALE AND THEN ALONG THE X-AXIS,
WE CAN JUST CONSIDER THIS THE REACTION PROGRESS.
SOMETIMES, YOU'LL SEE IT WRITTEN AS TIME,
COMMUNICATING THE SAME IDEA.
SO, FOR AN EXOTHERMIC REACTION, RIGHT,
THE PRODUCTS ARE GOING TO BE LOWER THAN THE REACTANTS.
SO THE REACTANTS ARE HIGHER IN ENERGY
AND THEN THE PRODUCTS ARE LOWER IN ENERGY.
SO WE'RE JUST GOING OVER THE FUNDAMENTALS HERE.
SO WE HAVEN'T BEEN GIVEN A SPECIFIC REACTION.
SO WE'LL JUST WRITE REACTANTS AND PRODUCTS HERE
TO HOLD THE PLACE
AND NOW LET'S BRING IN THIS ENTHALPY TERM, RIGHT?
SO THIS IS REPRESENTING DELTA H AND BECAUSE THE FINAL IS LOWER,
WE WOULD SAY THIS IS A NEGATIVE DELTA H, RIGHT?
THE ENERGY IS GOING TO A LOWER STATE.
SO THIS REPRESENTS THE HEAT GIVEN OFF IN THE REACTION.
SO THERE'S DIFFERENCE IN ENERGY
BETWEEN THE REACTANTS AND PRODUCTS,
IS THE HEAT RELEASED DURING THE REACTION.
OKAY. AND THEN TO JUST...
TO WRITE THIS OUT ONE OTHER WAY,
SO WE'VE TALKED ABOUT IT IN TERMS OF LINGUISTICS
AND WITH A GRAPH.
IF YOU WANT TO THINK IN TERMS OF A REACTION, RIGHT,
WE WOULD HAVE OUR REACTANTS
AND THEY'RE GOING TO PRODUCE A PRODUCT, RIGHT, PLUS HEAT, OKAY?
SO FOR AN EXOTHERMIC REACTION, THINK OF HEAT AS A PRODUCT.
WE'LL COMPARE THIS NOW TO THE ENDOTHERMIC REACTION.
SO BASICALLY, WE'RE JUST GOING TO TAKE EVERYTHING WE JUST DID
AND WE'RE GOING TO REVERSE IT.
WE'RE GOING TO USE THE SAME GRAPH, SAME STYLE,
ENERGY ON OUR Y-AXIS AND REACTION PROGRESS ON OUR X-AXIS.
BUT IN THIS CASE NOW, RIGHT, THE REACTION ABSORBS HEAT.
WHY DOES IT ABSORB HEAT?
BECAUSE THE PRODUCTS ARE HIGHER IN ENERGY.
SO WE HAVE A LOW ENERGY REACTANT
PRODUCING A HIGHER ENERGY PRODUCT.
SO WHEN WE DRAW THE REACTION ENTHALPY,
THE HEAT OF THE REACTION HERE, WE'RE GOING UP, RIGHT?
SO THAT'S THE POSITIVE DELTA H. ALL RIGHT.
SO THIS REPRESENTS THE HEAT THAT MUST BE ADDED TO THE REACTION
FOR IT TO OCCUR.
SO NOW WE'LL WRAP UP WITH...
SHOWING THIS AS A REACTION NOW,
SO THIS WOULD BE SAYING THAT WE HAVE THE REACTANTS
AND NOW WE HAVE TO ADD HEAT TO BE ABLE TO PRODUCE THE PRODUCTS.
SO IN THIS CASE, RIGHT, WE THINK OF HEAT AS A REACTANT.
AND WHENEVER WE'RE DISCUSSING A REACTION,
WHEN WE DESCRIBE IT IN ONE DIRECTION,
WHETHER IT'S NEGATIVE OR POSITIVE ENTHALPY,
IF WE REVERSE THE REACTION, WE'LL ALWAYS CHANGE THE SIGN.
ALL RIGHT.
NOW LET'S LOOK AT SOME REAL REACTIONS
SO THAT WE CAN PUT IN ACTUAL CHEMICAL FORMULAS
AND PUT THESE ALL TOGETHER.
SO WE'LL GO TO THE NEXT PAGE. ALL RIGHT.
SO LET'S PRACTICE DRAWING THE COMPLETE REACTION ENERGY DIAGRAM
FOR EACH OF THE REACTIONS BELOW,
MAKING SURE THAT WE LABEL OUR AXES, THE DELTA H
AND INCLUDE THE CHEMICAL FORMULAS OF THE REACTANTS
AND PRODUCTS.
LET'S ALSO CLASSIFY THE REACTIONS AS EXOTHERMIC
OR ENDOTHERMIC.
NOW, THE CONVENTION HERE, RIGHT,
IS THAT IF YOU LOOK AT THIS REACTION, METHANE WITH OXYGEN
TO PRODUCE CO2 AND WATER,
THIS NEGATIVE SIGN HERE IS TELLING US EXOTHERMIC, RIGHT?
BECAUSE WE TALKED ABOUT EXOTHERMIC
BEING NEGATIVE DELTA H.
SO THIS NEGATIVE SIGN IS TELLING US, RIGHT,
THAT THE HEAT IS A PRODUCT.
OKAY. SO WE CAN DRAW...
START DRAWING OUR REACTION ENERGY DIAGRAM,
ENERGY IS ALWAYS ALONG THE Y-AXIS
AND REACTION PROGRESS ALONG THE X.
MAKE SURE TO GET OUT THE POINTS IN DOING THE WORK, ALL RIGHT?
SO, HEAT IS A PRODUCT,
THAT'S TELLING US THAT THE PRODUCTS, RIGHT,
ARE LOWER IN ENERGY AND THE REACTANTS ARE HIGHER IN ENERGY.
SO WE'RE GOING TO DRAW OUR CURVE LIKE THIS.
IF YOU'RE WONDERING ABOUT THIS LUMP,
WE WILL ADDRESS THIS IN OUR FINAL VIDEO TUTORIAL.
SO FOR RIGHT NOW, WE'LL FOCUS ON THIS PART, RIGHT?
SO THE ENTHALPY, IT'S THE ENERGY DIFFERENCE
BETWEEN THE REACTANTS AND PRODUCTS
SO THERE'S OUR MINUS DELTA H
AND IN THIS CASE WE KNOW IT'S MINUS 213 KCALS PER MOL.
SO WE'VE ALREADY LABELED THIS ONE AS EXOTHERMIC,
THAT WILL BE MORE EXPLICIT.
OKAY.
SO NOW, TO FINISH THIS UP, WE'RE GOING TO WRITE--
HERE, WE DON'T HAVE--WE'RE NOT TALKING IN GENERAL TERMS,
WE HAVE A SPECIFIC REACTION.
SO THE REACTANTS ARE METHANE AND OXYGEN
AND THE PRODUCTS ARE CO2, WATER
AND THEN THE HEAT DESCRIBED BY THE GRAPH.
ALL RIGHT. ONE MORE REACTION PRACTICE, SLIDE THIS UP. OKAY.
THIS IS THE OTHER WAY TO COMMUNICATE
THE REACTION ENTHALPY.
HERE, WE NOTICE THAT THE REACTION ENTHALPY IS INCLUDED
AS A REACTANT.
SO BECAUSE THE ENTHALPY IS SHOWN AS THE REACTANT,
WE KNOW THAT THIS REACTION IS ENDOTHERMIC.
IF THIS WAS--IF THIS INFORMATION WAS SHARED
LIKE THE PREVIOUS EXAMPLE,
WE WOULD SHOW IT AS DELTA H PLUS 43 KCALS PER MOL, ALL RIGHT?
SO WE--THE POSITIVE SIGN WOULD TELL US IT'S ENDOTHERMIC
OR HOW IT'S WRITTEN AS A REACTANT TELLS US ENDOTHERMIC.
SO FOR THIS REACTION TO OCCUR, WE MUST ADD ENERGY
OR NOTHING WILL HAPPEN.
ALL RIGHT.
SO OUR REACTION ENERGY DIAGRAM, ENERGY IS ALWAYS ON THE Y-AXIS,
REACTION PROGRESS ON THE X,
SO THIS TIME, WE HAVE TO PUT ENERGY IN,
SO IT MEANS OUR REACTANTS ARE LOWER IN ENERGY
THAN OUR PRODUCTS.
SO WE HAVE TO PUT IN HEAT OR ENERGY, RIGHT?
AND THIS WOULD BE...
IN THIS CASE WE KNOW
HOW MUCH OR THE MINIMUM AMOUNT WE HAVE TO PUT
BECAUSE WE'RE GIVEN THE VALUE.
AND THEN TO FINISH UP OUR DIAGRAM,
WE WILL LIST THE ACTUAL REACTANTS AND PRODUCTS
FOR THIS REACTION, ALL RIGHT.
SO, THAT WILL COVER THE MAIN PART
OF CONNECTING REACTION ENERGIES TO THE REACTION
BUT THERE'S A VERY IMPORTANT APPLICATION OF THIS CONCEPT,
CALORIMETRY, THAT LINKS, COMES FULL CIRCLE WITH NUTRITION
AND THE CALORIE UNITS WE TALKED ABOUT AT THE--ON THE FIRST PAGE.
SO LET'S NOW LOOK AT THIS IMPORTANT APPLICATION
OF REACTION ENERGY.
SO, CALORIMETRY IS AN EXPERIMENTAL TECHNIQUE
TO MEASURE ENTHALPY CHANGES, RIGHT?
SO ENTHALPY, DELTA H, SO WE'RE TRYING TO MEASURE THAT.
SO, THE--AND THIS RELATES TO CONSERVATION OF ENERGY.
THE IDEA THAT THE HEAT LOST MUST EQUAL THE HEAT GAINED,
ALL RIGHT.
SO, TO FIGURE OUT, HOW DO THEY FIGURE OUT
THAT THERE WERE 350 CALORIES IN THAT MUFFIN?
RIGHT?
WELL, WHAT WE'RE GOING TO DO
IS WE'RE GOING TO DO A COMBUSTION REACTION
AND WE'RE GOING TO BURN THE FOOD, RIGHT?
SO THE HEAT LOST BY THE FOOD
IS GOING TO EQUAL THE HEAT GAINED BY THE CALORIMETER,
SO THAT'S THE DEVICE THAT'S BEEN DESIGNED
TO ABSORB ALL OF THESE HEAT
SO THAT WE KNOW HOW MUCH WAS RELEASED.
NOW, LET'S LOOK AT THE CONSTRUCTION OF THE CALORIMETER,
RIGHT?
SO HERE'S OUR FOOD
AND THEN WE'RE GOING TO HAVE SOME IGNITION WIRES, RIGHT,
TO START COMBUSTION
AND THEN FOR A COMBUSTION REACTION TO OCCUR, RIGHT,
WE NEED SOME OXYGEN TO BE THERE, PRESENT.
AND THEN WE HAVE, THIS IS ALL PART OF THE CALORIMETER
AND THIS HAS BEEN DESIGNED IN SUCH A WAY
TO ABSORB THE RELEASED HEAT.
THE CALORIMETER ABSORBS THE HEAT RELEASED FROM THE FOOD.
ALL RIGHT.
AND SO THEN ALL OF THE MEASUREMENTS
HINGE ON THIS THERMOMETER,
SO THERE'S A LOT THAT GOES INTO THIS,
THE DETAILS THAT WE'RE NOT GOING TO TALK ABOUT.
SO BASICALLY, THERE'S A FORMULA THAT'S BEEN DERIVED
THAT WE CAN LOOK AT THE CHANGE AND THE TEMPERATURE
AND WE CAN CONNECT--
THE INCREASE IN THE TEMPERATURE CAN BE CORRELATED
TO THE CALORIE CONTENT OF THE FOOD, ALL RIGHT?
SO WE'RE NOT GOING TO WORRY ABOUT THOSE DETAILS,
WE JUST WANT TO UNDERSTAND THE OVERALL CONCEPT, RIGHT?
SO A FORMULA CONVERTS, RIGHT, THE CHANGE IN TEMPERATURE,
THE INCREASE IN TEMPERATURE TO, RIGHT,
THE CALORIE CONTENT OF THE FOOD.
AND SINCE WE'RE TALKING ABOUT FOOD, WE'RE USING UPPERCASE C.
AND SO THIS OF COURSE IS A SUBJECT THAT HAS BEEN STUDIED
TO A GREAT DETAIL AND SO WHAT HAVE WE LEARNED ABOUT FOOD?
WELL, AS WE GO THOUGH THE COURSE, WE'RE GOING TO RECOGNIZE
THAT FOOD IS COMPRISED OF BASICALLY THREE BIOMOLECULES,
CARBOHYDRATES, PROTEINS AND FATS.
AND HERE'S SOME EXAMPLES OF WHERE WE WOULD FIND THOSE.
AND THEN WE'LL NOTICE THAT THE CALORIE CONTENT PER GRAM
OF CARBOHYDRATES OR PROTEINS IS THE SAME.
FATS ARE A VERY HIGH-ENERGY MOLECULE SO WE GET MORE CALORIES
FROM EACH GRAM OF FAT THAT WE CONSUME.
SO IN MY CLASS, I DON'T EXPECT YOU TO MEMORIZE THIS,
I'LL INCLUDE THIS INFORMATION ON ANY QUESTIONS.
LET'S FINISH UP BY PRACTICING A CALCULATION, ALL RIGHT?
SO, I THINK THIS WAS SOME GRANOLA,
I PHOTOCOPIED A LABEL OFF OF SOME GRANOLA
AND LET'S CALCULATE THE CALORIE CONTENT
FOR EACH OF THE BIOLOGICAL MOLECULES
ON THE NUTRITIONAL LABEL.
WELL, SINCE THE LABEL STARTS WITH FAT, LET'S START THERE.
THERE ARE NINE GRAMS OF FAT IN A SERVING OF THIS GRANOLA.
SO FOR FATS, ALL RIGHT, WE START WITH THE NUMBER OF GRAMS OF FAT
WE WOULD HAVE
AND THEN WE WOULD LOOK TO OUR TABLE
AND OUR TABLE TELLS US THAT THERE ARE NINE CALORIES
OF HEAT ENERGY FOR EVERY ONE GRAM OF FAT.
AND THEN WE HAVE TO HAVE CAREFUL ATTENTION
WHEN WE'RE READING THESE QUESTIONS
BECAUSE NOTICE THAT THAT'S A SCIENCE CALORIE.
SO, WE HAVE BEEN GIVEN THE INFORMATION IN FOOD CALORIES.
SO WE'RE GOING TO NEED TO WEAVE IN, RIGHT,
FOR EVERY FOOD CALORIE,
WE WOULD HAVE A THOUSAND SCIENCE CALORIES.
SO, WE PUNCH THESE VALUES INTO OUR CALCULATOR
AND IT'S GOING TO SPIT OUT 81,000 SCIENCE CALORIES
AND THEN WE'LL TAKE THIS OPPORTUNITY
TO DO A SIGFIG REVIEW.
THIS CAN BE VERY UNSATISFYING THOUGH
BECAUSE EVERYTHING HAS ONE SIGFIG.
SO, IF WE WERE GOING TO REPORT THIS,
WE WOULD SAY THAT WE HAVE 80,000 CALORIES FROM THE FAT.
AND NOW WE REPEAT THIS PROCESS TWO MORE TIMES,
LET'S LOOK AT THE CARBO, LET'S SEE WHAT'S NEXT ON OUR LABEL,
WE HAVE CARBOHYDRATES HERE, SO WE'LL GO AHEAD AND DO THE CARBS.
SO WE WOULD HAVE SIXTEEN GRAMS OF CARBOHYDRATES
AND THEN OUR CHART TELLS US THAT FOR EVERY GRAM OF CARBOHYDRATES,
WE WILL RECEIVE FOUR CALORIES OF ENERGY
AND THEN WE WILL CONVERT THAT FROM FOOD TO SCIENCE CALORIES.
AND OUR CALCULATOR SPITS OUT A VALUE
OF 64,000 SCIENCE CALORIES.
AND ONCE AGAIN, WE'RE LIMITED TO ONE SIGFIG.
SO IF WE'RE WATCHING OUR WEIGHT THAT'S A GOOD THING,
ONLY 60,000 CALORIES FROM THOSE CRABS.
AND THEN LAST BUT NOT LEAST, WE'LL LOOK AT THE PROTEIN.
SO THE PROTEIN ON OUR LABEL IS THREE GRAMS,
THREE GRAMS PROTEIN.
OUR CHART TELLS US THERE ARE FOUR CALORIES
FOR EACH GRAM OF PROTEIN AND THEN LAST BUT NOT LEAST,
THE QUESTION WANTS TO KNOW IN SCIENCE CALORIES,
SO WE'LL DO THAT LAST CONVERSION STEP.
AND THERE, CALCULATOR SPITS OUT 12,000 SCIENCE CALORIES.
BUT WE'RE LIMITED TO ONE SIGFIG.
SO WE WOULD REPORT THE ANSWER AS 10,000 CALORIES. OKAY.
SO, THIS TUTORIAL WAS VERY ALL-ENCOMPASSING
AND INTRODUCED THE ENERGY UNITS OF CALORIES,
BOTH SCIENTIFIC AND NUTRITION AND JOULES,
LOOKED AT HOW IT CONNECTS TO CHEMICAL REACTIVITY
WITH ENDOTHERMIC AND EXOTHERMIC REACTIONS
AND FINALLY A VERY USEFUL APPLICATION WITH CALORIMETRY.
PLEASE TAKE SOME TIME NOW TO WORK A FEW PRACTICE PROBLEMS
TO REINFORCE YOUR UNDERSTANDING.