13 - Chemical Kinetics Rates of Reactions

13 - Chemical Kinetics Rates of Reactions - Chapter 13:...

Info iconThis preview shows pages 1–2. Sign up to view the full content.

View Full Document Right Arrow Icon
Chapter 13: Chemical Kinetics: Rates of Reactions Chemical kinetics : the study of the speeds of reactions and the nanoscale pathways or rearrangements by which atoms and molecules are transformed from reactants to products Knowing kinetics allows us to control many kinds of reactions (i.e., combustion) 13.1Reaction Rate For a reaction to occur, reactant molecules must come together so that atoms can be exchanged or rearranged; atoms can move more in gas phase or solution Homogeneous reaction –one in which reactants and products are all in the same phase (gas or solution) For homogeneous reaction, four factors affect speed of reaction: o o Concentrations of reactants and sometimes products o Temperature at which reaction occurs o Presence of a catalyst and if present, its concentration Catalyst speed up reactions but undergo no net chemical change itself Heterogeneous reaction – take place at a surface that is interface between two different; increasing surface at which reaction occurs increases reaction rate; i.e., spray powder into air and combust vs. pile of powder Rate is the speed of any process and is the change in some measurable quantity per unit of time Reaction rate is the change in concentration of a reactant or product per unit time (independent of volume of reaction mixture) Reaction Rates and Stoichiometry o aA + bB cC + dD Rate = - Δ[A]/a Δt = - Δ[B]/b Δt = Δ[C]/c Δt = Δ[D]/d Δt o Rate of change in concentration of any of the reactants or products is multiplied by the reciprocal of the stoichiometric coefficient to find the rate of reaction o If the stoichiometric coefficients of the balanced equation are changed, the definition of reaction rate also changes Average Rate and Instantaneous Rate
Background image of page 1

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

View Full DocumentRight Arrow Icon
Image of page 2
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 09/28/2009 for the course CHEM 1A taught by Professor Nitsche during the Fall '08 term at University of California, Berkeley.

Page1 / 3

13 - Chemical Kinetics Rates of Reactions - Chapter 13:...

This preview shows document pages 1 - 2. Sign up to view the full document.

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