Atmosphere- 2 Air pollution Flashcards
What must happen with the reactants when a chemical reaction occurs?
Come together
In correct orientation
Enough energy (activation energy)
What does activation energy lead to?
temperature dependence
What happens to most reactions as they get hotter?
Get faster
Where does the energy come from for photochemical reactions?
Sunlight
What are thermal reactions driven by?
energy possessed by reactants
How do you calculate the rate of change of concentration?
Rate Law x stoichiometry
What does stoichiometry tell us?
relative numbers of reactant and product species destroyed / created per reactive
encounter
What does the rate of a chemical reaction tell us?
the rate of change of concentration of reactants or products
What does Rate Law tell us?
how/what the rate depends on
What is the rate of reaction like for an elementary reaction?
proportional to concentration of all reactants
What is the equation for temperature/ temperature dependence?
k= A exp (-Ea / RT)
What do the letters in the temperature dependence equation mean?
A= pre-exponential factor
Ea= activation energy (Joules per mole)
R= Gas constant
T= temp in Kelvin
What will the equation be like if there is positive temperature dependence?
Ea is positive
Rate constant increases with higher temp
What will the equation be like if there is negative temperature dependence?
Ea negative
Rate constant decreases with higher temp
What has happened to air quality in the UK since 1950’s?
substantially improved