Rate equations Flashcards
What is the rate of reaction?
The change in the amount of reactants or products over time.
How do you collect a gas produced during a reaction?
A gas syringe
How does a colorimeter work?
It measures the absorbance of the solution. The more concentrated a solution is the higher the absorbance.
What is the rate equation?
What does zero order mean?
If the concentration changes and the rate stays the same.
What does first order mean?
The change in the concentration is proportional to the change in the rate.
What does second order mean?
The change in the concentration is proportional to the change in the rate squared
What effect does an increase in k have on the rate?
The rate increases.
What factors affect the size of the rate constant?
The higher the temperature the higher the rate constant.
What are the units for rate?
mol dm -3 s-1
What is the initial rate?
The rate at the very start of the reaction.
How do clock reactions work?
You measure the time taken for a certain product to form as you vary the concentration of one of the reactants.
How can you tell when a desired product has been formed?
When there is a colour change.
What is the rate-determining step?
The slowest step determines the rate of the reaction.
What does the Arrhenius equation show us?
It shows us how the rate constant varies with temperature and activation energy.
What effect does an increase in activation energy have on the rate constant k?
The rate constant decreases.
What effect does an increase in temperature have on the rate constant k?
The rate constant increases.
What is the x-axis and y-axis on an Arrhenius plot?
x = 1/T
y = ln(k)
What does the gradient represent on an Arrhenius plot?
- Ea/R
How does an iodine clock reaction work?
- H2O2 + 2H+ + 2I- = I2 + 2H2O
- 2S2O3 2– + I2 → 2I– + S4O6 2–
- Most of the iodine from the first reaction will react with the limited sodium thiosulfate but the excess will remain in the solution and react with starch that produces the blue-black colour.
- The experiment is then repeated with varying concentrations of iodide ions while keeping the concentration of the others the same.
