Change in concentration of a reactant or product per unit time.
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How can rate be calculated?
Change in conc. of reactant or product / time taken for change.
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What are ways of measuring the rate of reaction?
1)Colorimetry.2)Change of conductivity.
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How can a concentration time graph be used to determine the rate of reaction?
Draw a tangent to the curve and find the gradient of the tangent to the curve.
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LEARN TO DRAW CONC TIME GRAPHS.
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What is activation energy?
The minimum energy required to start a reaction by the breaking of bonds.
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What are 5 factors that affect the rate of a reaction?
1)Temperature.2)Pressure (gas).3)Concentration(solutions).4)Surface Area (solids).5)Catalyst.
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Explain the effect of increasing concentration.
1)As conc. of reactant increases...2)Rate of reaction increases.3)More particles per unit volume.4)Increases number of successful collisions per unit time.
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Explain the effect of increasing pressure.
1)When pressure of gas increases...2)Rate of reaction increases..3)More particles per unit volume.4)Increased number of successful collisions per unit time.
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Explain the effect of increasing temperature.
1)As temperature increases..2)Rate of reaction increases.3)Average energy of particles increases.4)greater proportion of particles with energy above activation energy.5)Increased number of successful collisions per unit time.
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Explain the effect of increasing surface area.
1)Increasing Surface area of a solid causes..2)Rate of reaction to increase.3)More particles available to react.4)Increases number of successful collisions per unit time.
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Explain the essential features of the Boltzman Distribution.
1)No molecules with zero energy.2)Few very energetic molecules.3)Most have average amounts of energy.4)Area under curve is number of molecules.
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LEARN TO DRAW BOLTZMAN
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What is a catalyst?
Speeds up a reaction without being consumed by the overall reaction.
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Explain the effect of a catalyst in a catalytic converter.
1)Reactant molecules adsorb (stick) to surface of catalyst.2)Bonds weaken.3)Chemical reaction takes place on surface of catalyst with lower activation energy.4)Products desorb (fall off) surface of catalyst.
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What are 3 advantages of using a catalyst- explain why.
1)Reduced energy demand and emissions-lower temp required due to lower activation energy.2)Improved atom economy- different reactions can be used.3)Specific products can be prepared-catalysts are often enzymes (natural).
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What is a homogeneous catalyst?
Reactants and catalyst are in the same phase.
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Give 2 reactions in which a homogeneous catalyst is used.
1)Esterification- catalyst=sulfuric acid. 2)Oxidation of iodide ions with persulfate ions. Catalyst= Fe2+ or Fe3+.= LEARN EQUATIONS.
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What is a heterogeneous catalyst?
Reactants and catalyst are in different phases.
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Give 3 reactions in which heterogeneous catalyts are used.
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