- WELCOME TO THE VIDEO TUTORIAL FOR GAS LAWS.
WE'LL BEGIN WITH CONNECTING OUR UNDERSTANDING OF GASES
TO THE KINETIC THEORY OF MATTER.
SO, REMEMBER THAT GASES ARE SMALL PARTICLES
THAT MOVE RANDOMLY WITH RAPID VELOCITY.
AND THAT WE BASICALLY SAY, RIGHT,
WE SAID THAT THE KINETIC ENERGY IS MUCH GREATER
THAN THE POTENTIAL ENERGY.
SO, THAT THERE IS--
BASICALLY, WE CAN NEGLECT ANY INTERACTION
BETWEEN THE GAS MOLECULES.
AND THAT THE ACTUAL VOLUME OCCUPIED BY THE GAS MOLECULES,
RIGHT, THE SIZE OF THE MOLECULES THEMSELVES IS EXTREMELY SMALL
COMPARED TO THE SPACE BETWEEN THEM.
AND THEN, REMEMBER THAT THE KINETIC ENERGY WE--
AS WE INCREASE THE TEMPERATURE,
WE'RE GOING TO INCREASE THE KINETIC ENERGY
OF OUR GAS SAMPLE.
AND LAST BUT NOT THE LEAST,
THE GAS MOLECULES ARE IN CONSTANT MOTION
AND THEY MOVE RAPIDLY IN STRAIGHT PATHS.
SO, THEN WHEN-- IF THE GAS MOLECULES COLLIDE
INTO EACH OTHER THEY'RE JUST GOING TO BOUNCE OFF
LIKE BILLIARD BALLS AND KEEP GOING.
SO, NOW WE'RE GOING TO FOCUS ON THE GAS LAWS
THAT WE NEED TO HAVE FOR--
TO BE SUCCESSFUL IN OUR BIOLOGY CLASSES.
SO, THE GAS LAW THAT WE'RE GOING TO LOOK AT FIRST IS BOYLE'S LAW.
AND THIS IS ABOUT THE RELATIONSHIP
BETWEEN THE PRESSURE AND VOLUME OF GASES.
SO, THIS IS A INVERSE RELATIONSHIP.
IF WE HAVE A GAS SYSTEM
AT AN INITIAL PRESSURE AND AN INITIAL VOLUME,
IF WE CHANGE
THE PRESSURE WE'RE GOING TO HAVE TO CHANGE THE VOLUME.
AND THIS IS AN INVERSE RELATIONSHIP.
SO, THAT MEANS THAT IF WE INCREASE THE PRESSURE,
WE'RE GOING TO DECREASE THE VOLUME, RIGHT?
OR IF WE DECREASE THE PRESSURE,
WE'RE GOING TO INCREASE THE VOLUME.
SO, THE EXAMPLE THAT I LIKE TO GIVE
FOR YOU HERE IS WHEN WE FIRST STARTED EXPLORING DEEP
DOWN UNDERNEATH THE OCEAN,
THERE'S A LOT MORE PRESSURE
AT THE BOTTOM OF THE OCEAN THAN THERE IS A THE TOP.
SO, WE FOUND SOME LIFE FORMS DOWN THERE.
AND THESE LIFE FORMS WERE AT A VERY HIGH PRESSURE.
AND THE PEOPLE WERE SO EXCITED TO BRING THEM TO THE SURFACE
THAT THEY BROUGHT THEM UP RIGHT AWAY.
AND AS THEY BROUGHT THEM TO THE SURFACE,
THERE WAS LESS AND LESS PRESSURE.
AND GUESS WHAT HAPPENED,
THE LITTLE ORGANISMS EXPLODED, RIGHT?
THEIR VOLUME, RIGHT,
AS WE HAD LESS AND LESS PRESSURE,
THE VOLUME GOT BIGGER AND BIGGER AND BIGGER UNTIL IT EXPLODED.
SO, THAT'S KIND OF A GRUESOME EXAMPLE TO HELP YOU REMEMBER.
AT A MORE PERSONAL LEVEL, IT'S HOW WE BREATHE.
SO, WHAT HAPPENS WHEN WE BREATHE IS WE HAVE THE DIAPHRAGM.
AND AS WE TAKE IN A BREATH,
THE LUNGS EXPANDS AND INCREASE THE VOLUME.
AS WE INCREASE THE VOLUME,
WE DECREASE THE PRESSURE IN OUR LUNGS WHICH,
RIGHT, WHICH ALLOWS US TO INHALE.
SO, THIS IS WHAT CREATES OUR INHALE.
AND THEN, AS WE PUSH BACK UP ON OUR DIAPHRAGM,
THEN WE DECREASE THE VOLUME AND INCREASE THE PRESSURE.
AND THAT'S WHAT CREATES THE EXHALE.
ALL RIGHT? SO,
BOYLE'S LAW IS A VERY IMPORTANT LAW FOR US TO UNDERSTAND
BECAUSE WHEN WE STUDY THE RESPIRATORY SYSTEM,
IT'S GOING TO COME INTO PLAY.
SO, LET'S LOOK AT AN EXAMPLE OF HOW A--
WE CAN TIE A CALCULATION OF BOYLE'S LAW INTO OUR BREATHING.
SO, THE VOLUME OF AIR
IN A PERSON'S LUNGS IS 615 MILLILITERS AT A PRESSURE
OF 760 MILLIMETERS OF MERCURY.
SO, WE CAN LOOK AND SEE BY THE LANGUAGE, RIGHT,
SO THE MILLILITERS TELLS US THIS IS A VOLUME.
AND THE MILLIMETERS OF MERCURY TELL US THIS IS A PRESSURE.
IF YOU'RE UNCOMFORTABLE WITH THESE PRESSURE UNITS,
THERE IS A VIDEO TUTORIAL
ON PRESSURE UNITS THAT YOU CAN WATCH.
ALL RIGHTY.
SO, SINCE THESE ARE THE FIRST ONES WE'VE LOOKED AT,
WE'LL LINK THEM TOGETHER.
SO, THE MAIN THING, RIGHT,
SO THIS VOLUME AT THIS PRESSURE,
THAT'S THE IMPORTANT THING.
THE WORD AT THERE HELPS US KNOW
THAT THIS VOLUME IS LINKED TO THIS PRESSURE.
INHALATION OCCURS AS THE PRESSURE
IN THE LUNGS DROPS TO 752.
SO, THIS--
THESE UNITS TELL US THIS IS A PRESSURE.
AND WE ALREADY HAVE ONE PRESSURE,
SO THIS WILL BE OUR NEW PRESSURE.
TO WHAT VOLUME DID THE LUNGS EXPAND?
SO, THIS WOULD BE V2.
ALL RIGHTY.
SO, WE HAVE OUR CALCULATION HERE OR OUR FORMULA FOR BOYLE'S LAW.
AND WE WANT TO SOLVE FOR V2.
SO, IN SOLVING FOR V2 ALGEBRAICALLY,
THAT WOULD BE HERE. OKAY.
SO, WE STARTED WITH BOYLE'S LAW.
WE SOLVED FOR THE MISSING VARIABLE.
AND NOW, IT'S PLUGGING AND CHUGGING.
SO, WE PLUG IN THE VALUES OUR PRESSURE ONE,
760 MILLIMETERS OF MERCURY,
OUR INITIAL VOLUME, 615 MILLILITERS,
AND THEN OUR NEW PRESSURE, 252. SO,
NOTICE THAT, RIGHT, THE MILLIMETERS OF MERCURY,
THE PRESSURE UNITS CANCELLED JUST LIKE THEY--
WE WOULD EXPECT.
AND WE'RE LEFT WITH MILLILITERS WHICH IS A VOLUME UNIT.
SO, OUR CALCULATION LOOKS GOOD.
IT'S TIME TO PLUG THE DATA INTO OUR CALCULATOR
AND SEE WHAT WE GET.
ALL RIGHTY.
SO, THE VOLUME
OF OUR LUNGS HAS INCREASED TO 621.5 MILLILITERS, RIGHT?
SO, AS WE INCREASE THE VOLUME, WE DECREASE THE PRESSURE.
AND THAT ALLOWED THE AIR TO ENTER OUR LUNGS.
AND THEN, OF COURSE, SINCE WE'RE IN THE CLASS,
THE LAST THING WE WANT TO DO IS DOUBLE CHECK OUR SIG FIGS.
SO, WE HAD TWO SIG FIGS HER,
AND THREE HERE, AND THREE HERE.
SO, OUR FINAL RESULT WE SHOULD REPORT WOULD BE TO TWO SIG FIGS.
SO, THE VOLUME OF OUR LUNGS WOULD BE 620 MILLILITERS.
ALL RIGHTY.
SO, NOW WE'LL LOOK AT ANOTHER IMPORTANT GAS LAW
FOR UNDERSTANDING OUR RESPIRATORY SYSTEM.
AND THAT IS HENRY'S LAW.
SO, WHAT HENRY'S LAW DESCRIBES IS THAT THE AMOUNT
OF GAS DISSOLVED IN A LIQUID IS DIRECTLY PROPORTIONAL
TO THE PARTIAL PRESSURE OF THE GAS ABOVE THE LIQUID.
SO, BASICALLY, AS WE INCREASE THE PRESSURE, RIGHT, OF THE GAS,
WE INCREASE THE AMOUNT DISSOLVED.
AND I THINK THAT'S PRETTY INTUITIVE.
SO-- BUT LET'S MAKE SURE THAT EVERYBODY UNDERSTANDS.
SO, LET'S APPLY THE STATEMENT.
SEE IF WE CAN TAKE THIS KNOWLEDGE
AND APPLY IT AS WISDOM.
THERE ARE TWO UNOPENED BOTTLES
OF CARBONATED WATER THAT ARE AT THE SAME TEMPERATURE.
IF ONE IS OPENED AT THE TOP OF A MOUNTAIN,
AND THE OTHER AT SEA LEVEL,
WHICH ONE WILL PRODUCE MORE BUBBLES?
EXPLAIN YOUR REASONING.
ALL RIGHTY.
SO, LET'S LOOK, RIGHT,
SO HERE IF WE HAVE A CAN AT ONE ATMOSPHERE, ALL RIGHT?
SO, HERE'S OUR CAN OF SODA.
AND THEN, WE HAVE ONE AT THE TOP OF A MOUNTAIN.
THAT'S A REALLY TALL MOUNTAIN 14,000 FEET, ALL RIGHT?
SO, HERE, RIGHT, THERE IS A HIGHER PRESSURE,
RIGHT, ON THE--
ON THE LIQUID INSIDE THE CAN.
HERE WE HAVE THE LOWER PRESSURE, OKAY?
SO, IF WE POP THE TOPS, RIGHT,
WHICH ONE IS GOING TO PRODUCE MORE BUBBLES,
RIGHT, THE CAN
AT THE HIGHER ELEVATION THAT'S EXPOSED TO LESS PRESSURE, RIGHT?
SO, WHAT'S OUR EXPLANATION, RIGHT?
SO, THE LOWER--
THE LOWER ATMOSPHERIC PRESSURE,
RIGHT, ALLOWS MORE CO2 BUBBLES TO ESCAPE.
OKAY. YOU CAN THINK OF--
YOU CAN THINK OF THE PRESSURE
AS AN INVISIBLE FORCE FIELD PRESSING DOWN ON THE SURFACE.
SO, THE HIGH PRESSURE AT SEA LEVEL,
THE GAS BUBBLES WOULD HAVE TO FIGHT AGAINST THAT HIGH PRESSURE
TO BE RELEASED WHERE HERE,
THE GAS BUBBLES HAVE A MUCH LOWER PRESSURE
TO OVERCOME TO ESCAPE.
ALL RIGHTY.
LET'S LOOK AT A COUPLE MORE APPLICATIONS OF HENRY'S LAW.
HENRY'S LAW, THERE'S NOT REALLY A LOT OF CALCULATIONS HERE.
IT'S REALLY MORE CONCEPTUAL.
SO, FOR EXAMPLE,
WHAT HAPPENS TO THE SOLUBILITY OF OXYGEN GAS AND WATER
IN EACH OF THE FOLLOWING SITUATIONS?
THE PRESSURE OF OXYGEN
OVER THE SOLUTION IS DECREASED, RIGHT?
SO, THAT WOULD BE SIMILAR TO UP ABOVE.
AS WE DECREASE THE PRESSURE,
THEN THE CONCENTRATION OF OXYGEN IN THE SOLUTION,
RIGHT, WILL DECREASE.
ALL RIGHTY.
SO-- AND THAT'S THE SOLUBILITY, RIGHT?
SO, THE SOLUBILITY--
THE SOLUBILITY DECREASES AS THE PRESSURE DECREASES.
ALL RIGHTY.
AND THEN, THIS ONE--
THIS ONE ISN'T REALLY RELATED TO HENRY'S LAW,
BUT I COULDN'T THINK OF WHERE ELSE TO PUT IT IN,
SO I PUT IT HERE.
INTERESTINGLY ENOUGH,
WHEN WE HAVE GASSES AND WE HAVE GASSES IN SOLUTION,
THE RESULTS WITH TEMPERATURE ARE THE OPPOSITE
OF SOLIDS IN SOLUTION.
AS WE DECREASE THE TEMPERATURE OF A SOLUTION,
WE INCREASE THE CONCENTRATION OF THE GAS, RIGHT?
AND WE CAN LINK THAT TO THE KINETIC
AND POTENTIAL ENERGY,
SO, IF YOU'RE--
IF YOU'RE NOT FAMILIAR WITH KINETIC AND POTENTIAL ENERGY,
THERE IS A VIDEO TUTORIAL TO REMIND YOU.
BUT AS WE, RIGHT, AS WE LOWER THE TEMPERATURE,
WE LOWER THE KINETIC ENERGY.
THEN, THAT ALLOWS MORE GAS
TO DISSOLVE IN THE SOLUTION.
ALL RIGHTY. OKAY.
SO, THAT'S OUR SECOND GAS LAW.
WE HAVE ONE MORE GAS LAW THAT'S IMPORTANT
TO OUR RESPIRATORY SYSTEM.
AND THAT IS DALTON'S LAW.
NOW, DALTON'S LAW IS THE LAW OF PARTIAL PRESSURES.
AND SO, WHAT DALTON'S LAW TELLS US IS THAT IF WE HAVE A MIXTURE
OF GAS WHICH WILL DESCRIBE AS A PTOTAL, RIGHT?
SO, THE TOTAL OF PRESSURE
OF THAT MIXTURE IS INDEPENDENT OF THE OTHER GASES.
AND BASICALLY,
EACH GAS BEHAVES AS IF IT WAS BY ITSELF IN THE CONTAINER.
SO, RIGHT, SO, THIS WOULD BE THE PTOTAL.
THIS IS DESCRIBING THE MIXTURE.
AND THEN, HERE ARE--
WOULD BE THE INDIVIDUAL GASES IN THE MIXTURE.
OKAY. SO, WE CAN TAKE MATHEMATICALLY
AND WE CAN USE THE PARTIAL PRESSURES
TO DETERMINE THE PERCENT COMPOSITION, RIGHT?
THE PARTIAL PRESSURE OF EACH GAS
CAN BE CALCULATED BY MULTIPLYING THE TOTAL PRESSURE
BY THE GAS PERCENTAGE,
RIGHT? OR VICE VERSA
IF WE WANT TO FIND THE PERCENT OF AN INDIVIDUAL--
I THINK--
I THINK IT'S--
I SPELLED--
YEAH, OKAY. START OVER.
IF WE WANT TO FIGURE OUT THE PERCENTAGE
OF THE INDIVIDUAL GAS, RIGHT?
WE WOULD TAKE THE PARTIAL PRESSURE OF THIS GAS
AND DIVIDED BY THE TOTAL.
SO, BASICALLY ALL I DID WAS REARRANGE THIS EXPRESSION,
SO THAT WE COULD CALCULATE THE PERCENT
OF AN INDIVIDUAL GAS.
SO, THE CALCULATIONS
FOR DALTON'S LAW ARE PRETTY STRAIGHTFORWARD.
LET'S-- WE'LL JUST DO A COUPLE HERE
TO MAKE SURE EVERYONE'S GOT THE UNDERSTANDING.
SO, WE HAVE A MIXTURE OF GASES,
THERE'S NITROGEN, OXYGEN, AND HELIUM PRESENT.
AND THE TOTAL PRESSURE IS 760 MILLIMETERS OF MERCURY.
ALL RIGHT. SO, THE PTOTAL IS 760 MILLIMETERS OF MERCURY.
NOW, THE PARTIAL PRESSURE, THE PRESSURE
OF THE NITROGEN IS A HUNDRED AND TWENTY MILLIMETERS.
AND THE PARTIAL PRESSURE OF THE HELIUM IS 240. OKAY.
WHAT IS THE PRESSURE OF THE OXYGEN? ALL RIGHT.
SO, HERE WE'RE GOING TO USE THE TOP FORMULA.
SO, BASICALLY PTOTAL, RIGHT,
IS GOING TO BE PNITROGEN + PHELIUM + POXYGEN.
SO, THE QUESTION TELLS US THE TOTAL PRESSURE.
AND THE PRESSURE OF THE NITROGEN AND THE PRESSURE OF THE HELIUM.
SO, ALL WE HAVE TO DO IS SOLVE FOR THE PRESSURE OF THE OXYGEN.
SO, WE COULD SIMPLY TAKE THE 760
AND SUBTRACT THIS HERE, RIGHT?
SO, WE WOULD HAVE 760 MILLIMETERS
OF MERCURY MINUS 360 MILLIMETERS OF MERCURY.
SO, WE WOULD HAVE 400 MILLIMETERS OF MERCURY.
SO, THAT WOULD BE THE PRESSURE OF THE OXYGEN.
OKAY, SIG FIGS HERE.
WE'VE DONE ADDITION AND SUBTRACTION.
SO, OUR UNCERTAINTY WAS IN THE TENS PLACE.
SO, WE WOULD WANT TO PUT AN OVER BAR HERE
OR WE COULD USE SCIENTIFIC NOTATION
TO COMMUNICATE OUR SIG FIGS.
ALL RIGHTY.
AND NOW, WE WILL USE THE OTHER FORM OF DALTON'S LAW.
NOW, THAT WE HAVE THE PARTIAL PRESSURE OF OXYGEN,
WE CAN DETERMINE THE PERCENT OF OXYGEN IN THE MIXTURE, RIGHT?
SO, THE PERCENT OF OXYGEN WILL BE THE PRESSURE
OF OXYGEN/THE TOTAL PRESSURE X A HUNDRED.
ACTUALLY, I FORGOT TO PUT THAT THERE.
OKAY. SO, IN THIS CASE,
WE'VE DETERMINED THAT WE HAVE 400 MILLIMETERS
OF MERCURY OF OXYGEN.
AND THE TOTAL PRESSURE WAS 760.
SO, WE CAN DO THE CALCULATION.
AND WE CAN FIND THAT WE WOULD HAVE--
OUR CALCULATOR TELLS US 52.6% AND LOOKING AT OUR DATA,
WE'RE AT TWO SIG FIGS, SO 53% OXYGEN.
ALL RIGHTY.
SO, THERE ARE THE THREE MAIN GAS LAWS
THAT WE NEED FOR UNDERSTANDING OUR RESPIRATORY SYSTEM,
BOYLE'S LAW, HENRY'S LAW,
AND DALTON'S LAW OF PARTIAL PRESSURES.
SO, NOW I WOULD LIKE TO TAKE ON THIS LAST SHEET HERE
AND UNTIE THIS ALTOGETHER
AND SHOW YOU HOW IT APPLIES TO THE GAS EXCHANGE
OF OUR RESPIRATORY SYSTEM AND OUR BLOOD.
OKAY. SO, HERE WE'LL USE HENRY'S LAW
AND MOSTLY WITH A LITTLE BIT OF DALTON'S.
ALL RIGHT.
SO, HERE ARE OUR LUNGS.
AND LET'S MAKE SURE EVERYONE UNDERSTAND THIS CHART.
AND THEN, HERE IS OUR HEART.
AND THEN, THIS REPRESENTS OUR TISSUES, RIGHT?
SO, INSIDE OUR LUNGS, THE PRESSURE OF OXYGEN IS 159.
AND LET'S FOCUS ON OXYGEN FIRST, ALL RIGHT?
SO, USE THE DIAGRAM ABOVE TO EXPLAIN WHY OXYGEN DIFFUSES
FROM THE ALVEOLI IN THE LUNGS INTO THE BLOOD
AND FROM THE BLOOD INTO THE TISSUES OF THE BODY, RIGHT?
SO, INSIDE OUR LUNGS,
WE HAVE A HIGH PARTIAL PRESSURE OF OXYGEN.
AND IF WE LOOK AT THE ARTERIAL BLOOD,
WE SEE THAT THE OXYGEN IS ONLY A HUNDRED MILLIMETERS OF MERCURY.
SO, AS WE LOOK AT THE PRESSURE OF OXYGEN IN THE LUNGS, RIGHT?
IT'S A HUNDRED AND FIFTY-NINE MILLIMETERS OF MERCURY.
SO, IT'S GOING TO FORCE THE OXYGEN INTO THE ARTERIES
BECAUSE THEY ONLY HAVE A HUNDRED MILLIMETERS OF MERCURY.
OKAY. SO, NOW THAT ARTERIAL BLOOD,
IT'S BEEN OXYGENATED, RIGHT, BY THE PARTIAL--
BY THE PRESSURE OF THE OXYGEN,
FORCING THE OXYGEN INTO THE ARTERIAL BLOOD.
AND THEN, THE BLOOD IS TRAVELING ALONG INTO LIKE ITS--
TO OUR TISSUES.
AND THEN, NOTICE IN OUR TISSUES, RIGHT, OUR TISSUES
ONLY HAVE 30 MILLIMETERS OF MERCURY OF OXYGEN.
SO, THAT HUNDRED MILLIMETERS OF MERCURY OF OXYGEN IS GOING TO--
THE OXYGEN IS GOING TO FLOW INTO THE TISSUES.
NOW, LET'S LOOK AT THE RETURN TRIP.
WHEN WE LOOK AT THE RETURN TRIP, WE'RE FOCUSING ON THE CO2.
WELL, THE CELLS INSIDE OUR BODY ARE BUSY
UNDERGOING AEROBIC RESPIRATION AND PRODUCING CO2.
SO, IF WE LOOK AT THE PRESSURE OF CO2
IN OUR CELLS IT'S VERY HIGH.
AND I CAN ALMOST FIT THIS. OKAY.
SO, WE HAVE 60 MILLIMETERS OF MERCURY OF CO2 IN THE TISSUES.
SO, AS THAT--
AS THAT BLOOD COMES BY, IT DEPOSITS THE OXYGEN.
AND THEN, NOW IT BECOMES VENOUS BLOOD.
AND NOTICE HERE'S THE OXYGEN
OR THE CO2 HERE IS ONLY 46 MILLIMETERS OF MERCURY.
SO, THAT HIGH CO2 LEVEL IN THE TISSUES DRIVES THE CO2
INTO THE BLOOD THAT'S NOW THE VENOUS BLOOD.
AND THEN, THAT VENOUS BLOOD GOES UP TO THE HEART.
AND THEN, TRAVELS INTO THE LUNGS WHERE THE PRESSURE
OF THE CO2 IS INCREDIBLY SMALL AT 0.3
MILLIMETERS OF MERCURY.
AND SO, THAT'S HOW WE EXPEL THE CO2 OUT FROM OUR LUNGS,
FROM OUR TISSUES.
SO, I HOPE THAT YOU HAVE FOUND THIS VIDEO TUTORIAL HELPFUL
ON GAS LAWS AND THAT YOU'LL TAKE THE TIME
TO WORK A FEW HOMEWORK PROBLEMS TO REINFORCE THE CONCEPTS.