Rate Equations Flashcards
What are units of rate
Mol dm^-3 s^-1
What is the generalised rate equation
R = k (A)^m (B)^n
Effect of zero order
Concentration has no effect on rate of reaction
Effect of 1st order
Concentration is directly proportional to rate of reaction
Effect of 2nd order
Rate of reaction is proportional to concentration squared
What are the units of k, 1st order overall
S^-1
What are units of k, 2nd order overall
Mol^-1dm^3 s^-1
What are units for k, 3rd order overall
Mol^-2 dm^6 s^-1
What is order of reactant in large excess
Zero order
Why is a large excess of reactant zero order
Concentration stays virtually constant so doesn’t affect rate
What is the gradient of graph concentration x time
Rate of reaction
What graph has gradient rate of raw TiO2
Concentration against time
What speed for rate
Higher:
- concentration
- surface area
- temperature
What have the same rate on graph
Different volumes of same concentration
How can initial rate be calculated using graph
Take gradient at time=0
How you plot a rate equation
Plot log(rate) against log(Y)
What is the gradient of a log(rate) log(Y) graph
Oder n
How does increasing temperature affect k
K increases if temperature increases
When is k the same for all experiments
When all experiments are done at the same temperature
What is the Arrhenius equation
K = Ae^-EA/RT
How can the Arrhenius equation be rearranged
Ln k = Ln A - EA/RT
What can Ln k be replaced by in equation
Ln rate
Why can Ln k be replaced by Ln rate
As k is proportional to rate of reaction
Explain how do you find activation energy from a graph
- plot graph of Ln(rate) against 1/T
- gradient is -Ea/RT
Ea = - gradient x R
What are the units for activation energy
J mol^-1
What is the slowest step of a mechanism called
The rate determining step
Why does the slowest step of reaction control
Controls the overall rate of reaction
Is the molecularity of molecules in the slowest step the same as
The order of reaction for each substance
What order is a react if it appears twice in rate determining step
2nd order
