Rates of Chemical Reactions

Review of chemical reactions What are the two parts involved in a chemical reaction? – Reactants and products Chemical reactions can release energy or absorb energy. What are the terms for these types of reactions? Absorbs or requires energy: – Endothermic! Releases energy: – Exothermic!

Rates of reactions Many things are measured by their rate – Rate: how something changes over time – Ex. rate of driving – 100km/hour Rate of reaction describes the speed of the chemical reaction – Ex. how fast food spoils, how fast wood burns

How do you slow down or speed up a reaction? Inhibitors – SLOW DOWN – Slows down/ decreases the rate of a chemical reaction – E.g. chemical preservatives in cereal to keep it fresh Catalysts – SPEED UP – Speeds up/increases the rate of a chemical reaction – Same products but gets there faster – Ex. Enzymes are chemical substances in your body used to convert food to energy at a faster rate

What factors affect rate of reaction? FACTOR HOW IT AFFECTS RATE OF REACTION Temperature High temperature makes atoms move faster, increasing chances of colliding and reacting together = faster reaction rate ConcentrationThe more atoms are present, the higher chance of them colliding and reacting together = faster reaction rate Particle Size If particles are large most atoms are stuck inside and cannot react, but if there are many small particles many atoms are available to react = faster reaction rate

HOW PARTICLE SIZE AFFECTS CHEMICAL REACTION RATE!