Mr. Quinn & Ms. Tom March 14, 2014 Aim: What influences the rate of a chemical reaction? Do Now: Of the variables we have learned about that affect rate of reaction (temperature, surface area and pressure), which have a POSITIVE correlation (as one increases, the other increases)?

Let’s Try It Out! The effect of Concentration on Rate of Reaction As concentration increases, rate of reaction increases. As concentration decreases, rate of reaction decreases. Concentration affects the number of collisions of the particles. ConcentrationTime to React Low Medium High

New Concept: Catalyst What is it? A catalyst increases the rate of reaction. How does it work? A catalyst provides an alternate reaction pathway by decreasing activation energy Where do we see them? The most famous catalysts are enzymes

Let’s Try It Out! The effect of Catalysts on Rate of Reaction Note: A catalyst applies to ALL samples ReactionTime Catalyzed Uncatalyzed

Your Turn!

What is required for a chemical reaction to occur? 1.standard temperature and pressure 2.a catalyst added to the reaction system 3.effective collisions between reactant particles 4.an equal number of moles of reactants and products

Your Turn! As the pressure of a chemical reaction in the gas phase is increased, the rate of the reaction increases because 1.fewer particle collisions occur 2.more effective particle collisions occur 3.the required activation energy increases 4.the concentration of the reactants increases

Your Turn! Why can an increase in temperature lead to more effective collisions between reactant particles and an increase in the rate of a chemical reaction? 1.The activation energy of the reaction increases. 2.The activation energy of the reaction decreases. 3.The number of molecules with sufficient energy to react increases. 4.The number of molecules with sufficient energy to react decreases.

Your Turn! As the number of effective collisions between reacting particles increases, the rate of reaction 1.Decreases 2.Increases 3.remains the same

Your Turn! At STP, which 4.0-gram zinc sample will react fastest with dilute hydrochloric acid? 1.Lump 2.Bar 3.Powdered 4.sheet metal

Your Turn! Given the reaction: Mg + 2 H 2 O → Mg(OH) 2 + H 2 At which temperature will the reaction occur at the greatest rate? 1.25°C 2.50°C 3.75°C 4.100°C

Your Turn! Pepsin is an enzyme catalyst that speeds up the breakdown of proteins into amino acids. It does this by 1.Lowering the activation energy 2.Raising the activation energy 3.Increasing the surface area 4.Lowering the temperature

Your Turn! EcoR1 is a protein often used for genetic engineering. As the concentration of EcoR1 increases, the rate of reaction 1.Remains the same 2.Decreases 3.Increases

Your Turn! Two reactive gasses are contained in a piston together, and the pressure on the piston is halved. The rate of reaction will 1.Remain the same 2.Decrease 3.Increase

Your Turn! Hydrogen peroxide decays in sunlight. What concentration will decay the fastest? 1.1% 2.3% 3.10% 4.30%

Your Turn! Oxygen reacts with the surface of a solid zinc sample. Provide TWO methods for increasing the rate of this reaction. 1.Increase the temperature 2.Increase the surface area 3.Add a catalyst

Your Turn! RNase A catalyzes the hydrolysis of RNA into nucleosides in solution at 37° C. Provide TWO methods for decreasing the rate of this reaction. 1.Decrease the temperature 2.Decrease the concentration 3.Remove the catalyst