“Reaction Rates” Review of Alka Seltzer Lab

Collision Theory Reactions can occur: Reactions can occur: Very fast – such as a firecracker Very fast – such as a firecracker Very slow – such as the time it took for dead plants to make coal Very slow – such as the time it took for dead plants to make coal A “rate” is a measure of the speed of any change that occurs within an interval of time A “rate” is a measure of the speed of any change that occurs within an interval of time

Collision Model Key Idea: Molecules must collide to react.

Factors Affecting Rate 1) Temperature Increasing temperature always increases the rate of a reaction. 2) Surface Area Increasing surface area increases the rate of a reaction 3) Concentration Increasing concentration USUALLY increases the rate of a reaction 4) Presence of Catalysts: 5)Pressure Increasing the pressure increases the rate of the reaction.

Catalysts Catalyst: A substance that speeds up a reaction, without being consumed itself in the reaction Catalyst: A substance that speeds up a reaction, without being consumed itself in the reaction Inhibitors – interfere with the action of a catalyst; reactions slow or even stop Inhibitors – interfere with the action of a catalyst; reactions slow or even stop

Evidence of a Chemical Reaction: color change odor change temperature change bubbles or gas production solid formation

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