Reaction Rate Equations
In general, the reaction rate can be expressed by the formula:
Reaction Rate Equation Formula
Information :
v = reaction rate
k = reaction rate constant (the value depends on the type of reactant, temperature and catalyst)
x = order or reaction rate to reactant A
y = order or reaction rate to reactant B
x + y = order or total / overall reaction rate
Price k will change if the temperature changes. An increase in temperature and use of a catalyst will generally increase the price of k.
Reaction Order
"The reaction order states the magnitude of the effect of the reactant concentration on the reaction rate. "
Zero order reaction.
The reaction is said to be zero for one of the reactants, if the change in the concentration of the reactants does not affect the rate of the reaction. That is, as long as there are a certain amount; the change in reactant concentration does not affect the rate of the reaction.
The magnitude of the reaction rate is only influenced by the magnitude of the reaction rate constant (k).
Zero order reaction
Order of reaction one.
A reaction is said to be one for one of the reactants, if the reaction rate is directly proportional to the concentration of the reactant.
If the concentration of the reactants is tripled the reaction rate will be 31 or 3 times greater.
Order of reaction one
Reaction Order two.
A reaction is said to be 'double' to one of the reactants, if the reaction rate is the power of the reactants' concentration.
If the concentration of the reactants is tripled, the reaction rate will be 32 or 9 times greater.
Reaction Order two
Collision Theory
A substance can react with other substances if the particles collide with each other. The collision that occurs will produce energy to start the reaction.
The occurrence of collisions is caused by particles of matter always moving in an irregular direction.
Collisions between reacting particles do not always produce reactions. Only collisions that produce enough energy and the right direction of the collision can produce a reaction. Collisions like this are called effective collisions.
So, the reaction rate depends on 3 things:
Collision frequency
Reactant particle energy
Direction of collision
The minimum energy that must be possessed by reactant particles, so as to produce an effective collision is called activation energy or activation energy (Ea).
All reactions, both exothermic and endothermic, require Ea. A reaction that can take place at low temperatures means it has a low Ea. Conversely, a reaction that can take place at high temperatures, means it has a high Ea.
Ea is interpreted as the energy barrier between reactants and products. The reactant must be pushed so that it can pass through the barrier energy so that it can turn into a product.
Figure Collision Theory
Examples of Reaction Rate Questions
In the SO3 gas formation reaction according to the reaction: 2SO2 (g) + O2 (g) → 2SO3 (g), so the following data are obtained.
Determine:
a. The rate of increasing SO3
b. The rate of SO2 reduction
c. O2 reduction rate
Settlement:
Known :
Reaction equation: 2SO2 (g) + O2 (g) → 2SO3 (g)
Concentration data (in table).
Asked:
a. r SO3.
b. r SO2.
c. r O2.
Answer:
a. Δ [SO3] = [SO3] 3 - [SO3] 2 = 0.50 - 0.25 = 0.25 M
Δt = t3 - t2 = 40 - 20 = 20 s
So, the rate of SO3 increase is 1.25 x 10-2 M / s.
b. Because the SO2 coefficient = the SO3 coefficient, then:
r SO2 = - r SO3 = - 0.0125 M / s
So, the rate of SO2 reduction is -1.25 x 10-2 M / s
c. r O2 = - ½ x r SO3 = - ½ x 0.0125 = - 0.00625 M / s
Thus, the rate of O2 reduction is - 6.25 x 10-3 M / s