AL - Kinetics 1 Flashcards
What is a rate?
A change in something with respect to time
How can rate be measured? (5)
- Spectroscopic e.g. absorbance, fluorescence
- Temperature changes
- Mass changes
- Conductivity
- Electrochemical
What is the relationship between the rate of reaction and [Reactants] under zero-order kinetics?
Rate of reaction is independent of [Reactants]
For a zero-order reaction, what is the shape of the graph for:
- Concentration - Time
- Rate - Concentration
Concentration - Time
- Downward straight line with constant gradient of -k
Rate - Concentration
- Flat line (rate does not change with concentration)
What are the units for a zero-order reaction?
mol dm⁻³ s⁻¹
What is the relationship between the rate of reaction and [Reactants] under first-order kinetics?
Rate of reaction is directly proportional to [Reactants]
For a first-order reaction, what is the shape of the graph for:
- Concentration - Time
- Rate - Concentration
Concentration - Time
- Curved downward slope, exponential gradient
Rate - Concentration
- Straight line through 0,0, gradient of k
What are the units for a first-order reaction?
s⁻¹
What is the relationship between the rate of reaction and [Reactants] under second-order kinetics?
Rate of reaction is proportional to the product of the concentrations of two reactants
For a second-order reaction, what is the shape of the graph for:
- Concentration - Time
- Rate - Concentration
Concentration - Time
- Steeper curved downward slope
Rate - Concentration
- Curved upward slope
What are the units for a second-order reaction?
dm³ mol⁻¹ s⁻¹
What is half-life?
The time is taken for the concentration of [A] to reduce by half
What occurs to half life in all 3 order kinetics?
Zero-order: Half-life halves
First-order: Half-life is constant
Second-order: Half-life doubles
When should the initial rate (steepest slope) be measured? (2)
- Before [A] becomes limiting
- Before the concentration of the backward reaction becomes significant
