- WELCOME TO THE VIDEO TUTORIAL PART TWO FOR CHEMICAL REACTIONS.
THIS TUTORIAL IS GOING TO FOCUS ON COLLISION THEORY
WHICH IS A REALLY FUNDAMENTAL CONCEPT
THAT HELPS TO MAKE THE REACTIONS MORE LOGICAL AS WE DIG DEEPER.
LET'S GET STARTED. ALL RIGHTY.
SO, COLLISION THEORY STATES THAT FOR A CHEMICAL REACTION
TO OCCUR THE FOLLOWING CONDITIONS MUST BE MET,
WE HAVE TO HAVE A COLLISION.
THE REACTANTS MUST COLLIDE FOR A REACTION TO OCCUR.
SECONDLY, THEY HAVE TO HAVE ENOUGH ACTIVATION ENERGY.
SO, ACTIVATION ENERGY, WE WILL SYMBOLIZE E SUB A. SO,
NOT ONLY DO THEY HAVE TO COLLIDE,
THEY HAVE TO HAVE--
THE REACTANTS HAVE TO HAVE A MINIMUM TOTAL ENERGY, RIGHT?
SO, THE ENERGY OF THE COLLISION
MUST BE GREATER THAN OR EQUAL TO THE ACTIVATION ENERGY
WHICH YOU CAN THINK OF AS THAT MINIMUM ENERGY. ALL RIGHT.
AND THEN, IT'S NOT ENOUGH FOR THERE
TO BE A COLLISION OF THE HIGHEST--
OF THE-- AT LEAST, THAT MINIMUM ENERGY.
IT HAS TO HAVE THE CORRECT ORIENTATION.
THE REACTANTS MUST COME TOGETHER,
SO THAT WE CAN MAKE AND BREAK THE APPROPRIATE BONDS.
SO, I WOULD LIKE TO DEMONSTRATE THIS FOR YOU RIGHT NOW.
ALL RIGHT. SO,
IF WE VISUALIZE A SUCCESSFUL REACTION AS A LOUD CLAP, RIGHT?
SO, THERE WAS OUR REACTANTS COLLIDING
TOGETHER WITH ENOUGH ENERGY AND THE CORRECT ORIENTATION.
SO, LETS SEE WHAT HAPPENS IF WE DON'T HAVE ANYONE
OF THE THREE CRITERIA, RIGHT?
SO, THERE HAS TO BE A COLLISION, RIGHT?
IF MY HANDS DON'T HIT, IF THE REACTANTS DON'T HIT,
WE DON'T GET A REACTION.
AND IF THEY COME TOGETHER VERY GENTLY,
THERE IS NOT ENOUGH ENERGY TO GET THE REACTION.
AND THEN, LAST BUT NOT THE LEAST,
IF THE ORIENTATION IS WRONG,
WE WON'T GET OUR REACTION EITHER, RIGHT?
OUR REACTION IS SYMBOLIZED BY THE CLAP.
ALL RIGHT.
NOW, WE'LL DIG DEEPER
INTO EACH ONE OF THESE THREE CRITERIA.
SO, FIRST LET'S LOOK AT THE COLLISIONS, RIGHT?
THE REACTANTS MUST COME TOGETHER.
THIS IS AN IMPORTANT REASON FOR OUR SOLUTION CHEMISTRY.
REACTIONS TYPICALLY OCCUR IN A LIQUID OR A GAS.
SO, THAT THE REACTANTS ARE ABLE TO MOVE.
NOW, THE ACTIVATION ENERGY IS THIS MINIMUM ENERGY
WE NEED FOR THE COLLISION.
SO, LET'S LOOK AT EXAMPLES HERE.
SO, IF THIS--
IF THIS REPRESENTED REACTANT "A"
AND HERE WE HAVE REACTANT B. IN THIS EXAMPLE,
THE ENERGY OF THE COLLISION IS BELOW THE ACTIVATION ENERGY.
SO, WHEN WE LOOK AT THE PRODUCTS,
WE CONTINUE TO HAVE A AND B, RIGHT?
SO, WE HAVE A + B AND WE END UP WITH A + B. SO,
NOTHING CHANGED, RIGHT?
THIS WOULD BE NO REACTION.
ON THE OTHER HAND THOUGH,
IF THE COLLISION ENERGY
IS GREATER THAN OR EQUAL TO THE ACTIVATION ENERGY,
THEN WE HAVE OUR SAME ORIGINAL A AND B. HOWEVER,
WE WILL PRODUCE TWO NEW SUBSTANCES, C AND D. SO,
IF WE WROTE THIS AS A REACTION,
NOW, WE WOULD SAY THAT A + B PRODUCE NEW SUBSTANCES.
SO, THIS WOULD BE A SUCCESSFUL REACTION.
REACTION OCCURS.
ALL RIGHT. OKAY.
NOW, LETS GO ON TO ORIENTATION.
SO, WE'LL GO TO THE NEXT PAGE.
AND HERE IS A DIAGRAM TO REPRESENT ONE REACTION.
SO, REMEMBER THAT EVEN IF THE ACTIVATION REQUIREMENTS ARE MET,
SOME COLLISIONS STILL DO NOT OCCUR
BECAUSE NOT ONLY DO WE HAVE TO HAVE SUFFICIENT ENERGY,
BUT WE HAVE TO HAVE PROPER ORIENTATION.
SO, BEFORE WE LOOK AT THE POSSIBILITIES,
WE WANT TO STEP BACK FROM OUR REACTION
AND NOTE THE CHANGES, RIGHT?
WHAT CHANGES?
SO, WE SEE HERE
THAT WE HAVE NITROGEN IN A 1:2 RATIO WITH OXYGEN.
AND THEN, IT CHANGES TO 1:1.
AND THE CARBON STARTS WITH A 1:1 RATIO AND MOVES TO A 1:2.
SO, WE SEE THAT WE ARE--
WE LOSE ONE OXYGEN ATOM HERE.
AND WE'RE GOING TO GAIN ONE OXYGEN ATOM.
ALL RIGHT.
SO NOW, LET'S THINK ABOUT THE STRUCTURE OF OUR PRODUCT.
SO, WE'VE SPENT A LOT OF TIME WORKING WITH CARBON DIOXIDE.
SO, WE KNOW THE LEWIS STRUCTURE OF CARBON DIOXIDE.
SO, WE KNOW THAT THE CARBON ATOM IS SANDWICHED
BETWEEN THE TWO OXYGEN ATOMS.
NOW, LETS LOOK AT THESE THREE POSSIBLE SCENARIOS
TO SEE WHICH ONE WOULD SUPPORT THE CORRECT ORIENTATION.
NOTICE HERE THAT WE HAVE O TO O INTERACTION.
AND THAT'S NOT GOING TO CREATE OUR DESIRED PRODUCT.
SO, THIS WOULD BE AN IMPROPER ORIENTATION, NO REACTION.
WHEN WE LOOK AT THE NEXT EXAMPLE THOUGH,
WE SEE THAT WE HAVE A CARBON TO OXYGEN INTERACTION AND NOTICE
THAT THIS INTERACTION GIVES US THE CORRECT ALIGNMENT
TO PRODUCE OUR PRODUCT.
SO, THIS WOULD BE A CORRECT--
WE WOULD GET A SUCCESSFUL REACTION
HERE BECAUSE WE HAVE THE PROPER ORIENTATION.
AND THEN, ONE LAST EXAMPLE, HERE,
NOTICE THAT WE HAVE THE NITROGEN AND THE OXYGEN INTERACTING.
AND THAT DOES NOT CREATE OUR FINAL PRODUCT, SO ONCE AGAIN,
NO REACTION. OKAY.
AND THEN, TO TIE THIS ALL TOGETHER, RIGHT?
LET'S THINK ABOUT WHAT HAPPENS IF THE NITROGEN DIOXIDE
AND THE CARBON MONOXIDE COLLIDE WITH THE CORRECT ORIENTATION.
HOWEVER, THE COLLISION ENERGY IS BELOW THE ACTIVATION ENERGY.
WHAT HAPPENS?
NOTHING, RIGHT?
FOR A CHEMICAL REACTION TO OCCUR,
WE HAVE TO HAVE ALL THREE EVENTS SIMULTANEOUSLY.
WE HAVE TO HAVE THE COLLISION WITH SUFFICIENT ENERGY
AND THE CORRECT ORIENTATION.
SO, I'M NOT SURE HOW MANY PRACTICE PROBLEMS
OR HOMEWORK PROBLEMS THERE ARE FOR THIS TOPIC.
BUT IT'S A VERY FUNDAMENTAL UNDERSTANDING THAT WILL
SUPPORT YOU AS YOU WORK THROUGH OTHER REACTION QUESTIONS.