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Flashcards in 5 kinetics Deck (10):
1

kinetics

the study of factors that affect the rate of chemical reactions - how quickly they take place

2

species

a term used by chemists to refer to an atom/molecule/ion

3

activation energy (Ea)

the minimum energy that a particle needs in order to react; the energy (enthalpy) difference between the reactants and the transition state

4

transition state / activated complex

the species that exists at the top of the curve of an enthalpy diagram - some bonds are being broke, some made - it has extra energy and is unstable

5

Maxwell-Boltzmann distribution (4)

the distribution of energies (and therefore speeds) of the molecules in a gas or liquid
1. no particles have 0 energy
2. most particles have intermediate energies
3. few have v high energies
4. average energy is not most probable energy

6

rate of reaction

the change in concentration of a substance in unit time

7

what is a catalyst, how catalysts work

a substance that alters/increases the rate of a chemical reaction but is not changed in chemical composition or amount in the reaction.
by lowering the Ea by providing an alternate reaction pathway
does NOT affect the enthalpy change of the reactions, nor the position of equilibrium in a reversible reaction

8

adsorption

the adhesion of atoms, ions or molecules from a gas, liquid or dissolved solid to a surface, creating a film of the adsorbate on the surface of the adsorbent

9

desorption

the release of an adsorbed substance from a surface

10

factors that affect the rate of chemical reactions (5)

1. increasing temp - increases speed of molecules > increasing energy and no. of collisions

2. increasing conc of a sol - more particles, more collisions are likely

3. increasing pressure of a gas reaction - more molecules/atoms in a given volume, more collisions likely

4. increasing s.a. of solid reactants - the greater the total s.a. of solid, the more of its particles are available to collide w molecules in gas/liquid > more sites for reaction

5. using a catalyst - changes rate of reaction by providing alternate reaction pathway by lowering Ea wo/ getting used up/changed