CHAPTER 2
CHEMICAL KINETICS
REACTION RATE EXPRESSION
rate=Δ[B]/Δt=−Δ[A]/Δt
1) instantaneous rate - can be at any point and construct tangen line 2) initial rate - the instantaneous rate at the moment reactants are mixed
rate expression that is not 1:1 expression
EXAMPLE:
2HI(g) → H2(g) + I2(g), rate: -1/2Δ[HI]/Δt =Δ[H2]/Δt =Δ[I2]/Δt
FACTORS AFFECTING RATE OF REACTION
to achieve a successful collision
1) Chemical nature of the reactants- some of the chemical have their own nature of reactants.
2) Surface area- the smaller the surface area, the lower the rate of reaction
3) Concentration- the higher the concentration, the higher the rate of reaction
4) Temperature- the higher the temperature, the higher the rate of reaction
5) Catalysts- catalysts are substances that increase the rate of chemical reactions without being used up
INTEGRATED RATE LAW
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SECOND ORDER
ZERO ORDER
FIRST ORDER
1/[A]= kt + 1/[A]o
[A]= -kt + [A]o
ln[A]= -kt + ln[A]o
HALF LIFE
ZERO ORDER
T1/2= [A]o/2k
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FIRST ORDER
T1/2= ln/k
SECOND ORDER
T1/2= 1/k[A]o
ARHENIUS EQUATION
K= Ae^-Ea/RT