Controlling chemical Reactions

1. Controlling chemical Reactions • Background information you need to know • What is the difference between matter and energy? ______________________________ ____________________________________________________________________________________________________________________________________________________________

2. Controlling chemical Reactions • Matter= • Anything that has mass and takes up space. • Matter is all around you. • Examples of matter; _____________________ ____________________________________________________________________________________________________________________________________________________________

3. Controlling chemical Reactions • Energy= • The ability of a physical system to do work. • There are several different types of energy • For now we will focus on Kinetic energy • Kinetic energy is the energy of motion. • All atoms have kinetic energy. The more heat an atom has the faster it moves therefore it has more kinetic energy.

4. Controlling Chemical Reactions • Activation Energy= • The minimum amount of energy needed to start a chemical reaction • All chemical reactions need activation energy to get started

5. Controlling chemical reactions • Exothermic reaction= • Release energy usually in the form of heat. • Because energy is released you do not need continuous activation energy to keep it going. • Ex to start a fire you need a spark, once the fire is going good you do not need to keep adding extra sparks to keep it going.

6. Controlling chemical reactions • Endothermic reaction= • These reactions need energy to get them going, but they also need continuous energy to keep them going. • These reactions absorb heat/energy. • Baking or cooking something is an endothermic reaction if you take away the heat it will stop cooking. You need to continually supply energy to keep the reaction going.

7. Controlling chemical reactions • There are 5 ways that we can control chemical reactions • Surface area • Temperature • Concentration • Catalysts • Inhibitors

8. Controlling chemical reactions • Surface area • What is surface area? • The amount of area that is exposed to the environment. • Is it easier to start a fire using very small tinder, or a large log? Why? • Increased surface area = faster chemical reaction. Decreased = slower reaction

9. Controlling chemical reactions • Temperature • What happens to the movement of particles as temperature increases? • Particles move faster, therefore reactants can come in contact with each other more often. • Increased temp = faster chemical reaction • Decreased temp = slower chemical reaction

10. Controlling chemical reactions • Concentration • The more reactants you have the larger the chemical reaction can get and the faster it will happen. • If you want a large fast burning fire add more fuel, and more oxygen.

11. Controlling chemical reactions • Catalysts • Catalysts make chemical reactions go faster by lowering activation energy. • Catalysts bring reactants together so that they can react. • Catalysts are like match makers. • Enzymes in your body are catalysts

12. Controlling chemical reactions • Inhibitors • Inhibitors slow down chemical reactions by keeping reactants away from each other.