10 - Chemical Kinetics

10 - Chemical Kinetics - Chemical Kinetics How fast is it?...

Info iconThis preview shows pages 1–13. Sign up to view the full content.

View Full Document Right Arrow Icon
    Chemical Kinetics How fast is it?
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
    Consider a general reaction: A + 2 B   3 C Kinetics is all about the  rate  at which a reaction occurs.  How fast are the reactants turned into products?
Background image of page 2
    Kinetics is all about the  rate  at which a reaction occurs.  How fast are the reactants turned into products? Consider a general reaction: A + 2 B   3 C There are a number of equivalent ways  of looking at the rate of the reaction
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
    A + 2 B   3 C If I want to measure the rate, I need to look at  the  change  in something.
Background image of page 4
    A + 2 B   3 C If I want to measure the rate, I need to look at  the  change  in something. I have 3 somethings:
Background image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
    A + 2 B   3 C If I want to measure the rate, I need to look at  the  change  in something. I have 3 somethings:  I could look at how fast A disappears.  I could look at how fast B disappears.  I could look at how fast C appears. All 3 representations of the rate should be  equivalent!
Background image of page 6
    Rate The  rate  of a reaction is how fast it is occurring.  It  is a measure of the  change in concentration  of  the chemical species involved. 
Background image of page 7

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
    Rate as a function of time For my generic reaction: A + 2 B   3 C I have 3 different chemical species: A, B, and C. I can measure the rate in terms of ANY OF THE 3  COMPOUNDS
Background image of page 8
    Rate as a function of time A + 2 B   3 C Rate is  Δ concentration/Δ time Or Δ[A]/Δt – the change in [A] per unit time Δ[B]/Δt – the change in [B] per unit time Δ[C]/Δt – the change in [C] per unit time
Background image of page 9

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
    Relationship between the different  rates A balanced equation has stoichiometry.  This  stoichiometry has meaning. A + 2 B   3 C If 1 mole of A reacted, 2 moles of B MUST have  reacted also. If 1 mole of A reacted, 3 moles of C MUST have  been produced.
Background image of page 10
    The Algebra of rates So, applying stoichiometry, for a given unit of time: Δ[C] = -3 Δ[A], Δ[B] = 2 Δ[A], 2 Δ[C] =-3 Δ [B] Or, in terms of the rates, themselves: 2 Δ[A]/Δt = Δ[B]/Δt (or, Δ[A]/Δt = ½ Δ[B]/Δt)  3 Δ[A]/Δt = Δ[C]/Δt (or, Δ[A]/Δt = -1/3 Δ[C]/Δt)  3 Δ[B]/Δt = 2 Δ[C]/Δt (or, Δ[B]/Δt = -2/3 Δ[C]/Δt) The negative sign is because C appears as A or B disappears.
Background image of page 11

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
    Practical Considerations You can monitor the concentration of any species that is  convenient to measure. The rate is then calculated by taking the change in 
Background image of page 12
Image of page 13
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 04/17/2008 for the course CHEM 1011.216.0 taught by Professor Joelanzafame during the Winter '07 term at RIT.

Page1 / 71

10 - Chemical Kinetics - Chemical Kinetics How fast is it?...

This preview shows document pages 1 - 13. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online