kinetics rate constant, rate law, reaction rate.....

[sankara]

two questions

1) why does the concetration of a product affect the rate constant for a reaction (according to EK)

2) can someone please explain what's the difference between rate constant, rate law, reaction rate and reaction order...and what factors influence them.
I though I used to understand them but I guess not

cheers!

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[JSU]

1. The rate constant is a specific, experimental number for a certain reaction under certain conditions. Thus, an increase in concentration of reactants means that they will either collide more often or will be oriented more often when they do collide (I think there are a few models). This has an affect on the speed at which the reaction proceeds.

2. Dont have time for this one right now

EDIT: 2. Rate constant is the rate determined under a certain set of conditions, this does not tell us what happens when variables are changed. The rate law eg. R[X][Y] mathematically shows us what happens when a reactant concentration changes. This then equals the reaction rate. Reaction order is eg. 2X --> Y + Y, the rate law is probably R[X]^2 therefore the reaction is second order. (X --> 2Y would have a rate law of R[X] so it would be first order)

 

[wagmanager]

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[luctoretemergo]

two questions

1) why does the concetration of a product affect the rate constant for a reaction (according to EK)

2) can someone please explain what's the difference between rate constant, rate law, reaction rate and reaction order...and what factors influence them.
I though I used to understand them but I guess not

cheers!

Correct me if I'm wrong...
Rate law is rate of reaction where foward reaction is pdts/reactants (include coeff's if elementary if multi step reaction w/ slow step gets more complicated), reverse rxn rate is rcts/products. The order of the reactants and overall reaction depends on the behavior of the rate when concentrations are altered. Rate of the reaction is affected by temp, pressure, conc of reactants.

Rate constant is a specific value under set conditions, value depends on press, catalysts, and temperate; always increases with temperate (inc temp = inc collisions so more likely to achieve sufficient KE will occure every second), whereas the other factors (ie pressure) depend on specific situation.

 

[docelh]

1. Blatantly incorrect assertion.

2. Study the Kinetics chapter of your Gen Chem textbook. Again. And again. And again. And Again.