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STABILITY GUIDANCE
The
Arrhenius Equation of Svante Arrhenius (1903 Nobel Prize winner)
Common sense and chemical
intuition suggest that the higher the temperature, the faster a given chemical
reaction will proceed. Quantitatively this relationship between the rate
are action proceeds and its temperature is determined by the Arrhenius Equation.At
higher temperatures, the probability that two molecules will collide is
higher. This higher collision rate results in a higher kinetic energy, which
has an effect on the activation energy of the reaction. The activation energy
is the amount of energy required to ensure that a reaction happens.
This calculator
calculates the effect of temperature on reaction rates using the Arrhenius
equation.
k=A*exp(-Ea/R*T)
Where
k is the rate coefficient, A is a constant, Ea is the activation
energy, R is the universal gas constant, and T is the temperature (in degrees
Kelvin).
R has the value
of 8.314 x 10-3 kJ mol-1K-1
Illustrative
Data
To determine the incubation
time necessary for stability claims using the Arrhenius equation
a) Q10 =
2.0 (conservative; “Rule of Two”. For every 10 degree increase
in temperature the rate of degradation doubles)
b) Room temperature = 23C(Controlled
room temperature) RT is defined as 20 to 25C
c) Acceleration Time = Time
at RT/Q10(T2-T1/10)
For T2= 45C, T1 = 23C and
Q10=2.0 and time at T1 = 12 months (365 Days)
T2-T1
= 22C
Acceleration
Time = 12/222/10
= 12/22.2
= 12/4.6
= 2.6 Months at 45C = 1 Year at 23C.
|
Time
at Room Temperature (Years) |
Time
at 45C (Days) |
|
1 |
79 |
|
2 |
158 |
|
3 |
237 |
|
4 |
316 |
|
5 |
395 |
If
Q10 = 4, then
|
Time
at Room Temp (Years) |
Time
at 45C (Days) |
|
1 |
17 |
|
2 |
35 |
|
3 |
52 |
|
4 |
69 |
|
5 |
87 |