CONTROLLING CHEMICAL REACTIONS CHAPTER 1 SECTION 3 ENERGY IN CHEMICAL REACTIONS

ENERGY IN CHEMICAL REACTIONS EXOTHERMIC – WHEN MORE ENERGY IS RELEASED THAN WHAT YOU START WITH ENERGY OUT- FEELS HOT) ENDOTHERMIC- WHEN MORE ENERGY IS PRESENT THAN WHEN YOU STARTED (ENERGY IN –FEELS COLD)

GETTING REACTIONS STARTED IF WE LOOK AT A PIECE OF PAPER IT IS NOT BURNING (NO CHEMICAL REACTION OCCURING) HOW CAN WE GET THE CHEMICAL REACTION OF BURNING TO START? RIGHT- WE NEED TO HEAT THE PAPER UP TILL IT CATCES ON FIRE. ACTIVATION ENERGY- THE AMOUNT OF ENERGY NEEDED TO START A CHEMICAL REACTION

RATES OF CHEMICAL REACTIONS CONCENTRATITHON- THE AMOUNT OF ONE SUBSTANCE IN GIVEN VOLUME OF ANOTHER. EX WHICH IS MORE CONCENTRATED A. 1 TEASPOON OF SUGAR IN 100 ML OR B. 10 TEASPOONS OF SUGAR IN 100 ML THE MORE CONCENTRATED THE FASTER THE REACTION

RATES OF CHEMICAL REACTIONS IMAGINE WHICH DRINK WOULD BE SWEETER THE 1 OR 10 TEASPOON LIQUID? IT WOULD REACT FASTER WITH YOUR TONGUE. THE MORE CONCENTRATED A SOLUTION THE FASTER THE REACTION WILL OCCUR BECAUSE THERE IS MORE LIKELY HOOD THAT THE PARTICLES WILL TOUCH EACH OTHER AND REACT

SURFACE AREA WHEN A SOLID AND A LIQUID OR GAS REACT ONLY THE PART ON THE OUTSIDE THAT IS TOUCHING THE LIQUID OR GAS REACTS. IF YOU BREAK THE SOLID INTO PIECES THEN MORE OF THE SURFACE AREA WILL COME IN CONTACT WITH THE LIQUID OR GAS AND REACT,

SURFACE AREA THINK ABOUT A SUGAR CUBE IF YOU PUT IT IN HOT COFFEE IT WILL DISSOLVE- ONLY ON THE OUTSIDE (THE PART THAT IS TOUCHING THE HOT COFFEE) EVENTUALLY IT WILL ALL DISOLVE BUT FROM THE OUTSIDE IN.

LOOK AT FIGURE 20 IF YOU WERE TO PUT A MATCH INTO A PILE OF FLOUR THE MATCH WOULD GO OUT. WHY DID THE FLOUR IN THE GRAIN ELEVATOR REACT SO VIOLENTLY?

TEMPERATURES HEAT is KINETIC energy (energy of motion) The more kinetic energy the faster the reactants move and the more likely the will hit each other and react

CATALYST Way back we discussed proteins and we discussed a protein that SPEEDS UP a chemical reaction in living organisms______________. Imagine that our body needed a chemical reaction to occur to produce something that we needed to stay alive. But the temperature needed to be 150 degrees for the reaction to occur.

CATALYST So if we can’t get the product WE DIE If we heat up our body to 150 degrees so the reaction can occur WE DIE SO A catalyst (ENZYME) is produced that lowers the heat of activation (the temperature needed to start the reaction ) to 98.6- so WE LIVE

INHIBITOR A material that is used to SLOW DOWN a chemical reaction NITRO GLYCERINE is a liquid that BLOWS THINGS UP. It is very UNSTABLE- if you drop it YOU BLOW UP ALFRED NOBEL added WOOD CHIPS to the liquid and stabilized it- you could drop it ,bang it and throw it and it wouldn’t blow up – It was the invention of DYNAMITE