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Kinetics | Rate Equations and Order of Reactions | A level H2 Chem | Making Sense Chem
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A LEVEL CHEMISTRY!!
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In today's video, we will be re-looking at the most important concepts in the chapter Kinetics!
0:00 Introduction
1:35 Rates of reactions
2:02 Rate equations
3:29 Rate constant and determining its units
5:50 Determining order of reactions when given rate
9:17 Determining order of reactions when given time
Rates of reactions
Rate of reaction is defined as the change in amount or concentration of reactants or products per unit time.
Instantaneous rate : Draw tangent and measure it's gradient at any time point on the concentration-time graph
Initial rate : Draw tangent and measure it's gradient at point t=0 on the concentration-time graph
Average rate : Draw tangent and measure it's gradient between two points on the concentration-time graph
Rate equations
The rate equation is an experimentally determined expression of the rate of reaction in terms of the concentration of the reactants.
A simple rate equation is for the reaction A + 2B ➝ C is given by rate = ????
Rate equation units on left have to always be equal to those on the right, make k the subject of the equation and solve for the units (division of both sides of the rate equation).
The overall order of reactions is given by the total sum of the order of reactions with respect to each reactant.
Value of rate constant, k, is affected by both temperature and activation energy.
Determining order of reactions when given rate
Can be determined through two main methods, inspection and mathematical.
Inspection : involves observing and comparing the rate in which the concentration of one reactant is kept constant while the concentration of the other reagent is changed.
Mathematical : (LAST RESORT METHOD) when no 2 experiments with concentration of any reactant is kept constant.
Produce the rate equations for any 2 experiments.
Solve for order of reaction by dividing one rate equation by the other.
Determining order of reactions when given time
When a fixed amount of product is produced across the experiments, use the inverse relationship of rate and time to measure the rate of reactions.
Create an additional column beside time and fill in the rate of the equations.
Use either inspection or mathematical method to solve for the order of reactions.
music by:
In today's video, we will be re-looking at the most important concepts in the chapter Kinetics!
0:00 Introduction
1:35 Rates of reactions
2:02 Rate equations
3:29 Rate constant and determining its units
5:50 Determining order of reactions when given rate
9:17 Determining order of reactions when given time
Rates of reactions
Rate of reaction is defined as the change in amount or concentration of reactants or products per unit time.
Instantaneous rate : Draw tangent and measure it's gradient at any time point on the concentration-time graph
Initial rate : Draw tangent and measure it's gradient at point t=0 on the concentration-time graph
Average rate : Draw tangent and measure it's gradient between two points on the concentration-time graph
Rate equations
The rate equation is an experimentally determined expression of the rate of reaction in terms of the concentration of the reactants.
A simple rate equation is for the reaction A + 2B ➝ C is given by rate = ????
Rate equation units on left have to always be equal to those on the right, make k the subject of the equation and solve for the units (division of both sides of the rate equation).
The overall order of reactions is given by the total sum of the order of reactions with respect to each reactant.
Value of rate constant, k, is affected by both temperature and activation energy.
Determining order of reactions when given rate
Can be determined through two main methods, inspection and mathematical.
Inspection : involves observing and comparing the rate in which the concentration of one reactant is kept constant while the concentration of the other reagent is changed.
Mathematical : (LAST RESORT METHOD) when no 2 experiments with concentration of any reactant is kept constant.
Produce the rate equations for any 2 experiments.
Solve for order of reaction by dividing one rate equation by the other.
Determining order of reactions when given time
When a fixed amount of product is produced across the experiments, use the inverse relationship of rate and time to measure the rate of reactions.
Create an additional column beside time and fill in the rate of the equations.
Use either inspection or mathematical method to solve for the order of reactions.