Chemical Industury Flashcards
Rate of reaction=
The change in the amount of products per unit time
How can you measure the rate of a reaction?
pH change Volume of gas given off Loss of mass Colour change Titration
What is the general rate equation?
rate=k[A]^m[B]^n
What are m and n in the rate equation?
The orders of reaction with respect to A/B
The sum gives the overall order of reaction
What does k represent in the rate equation?
The rate constant- the bigger it is, the faster the reaction. k is affected by temperature- as the temperature increases, k also increases
What are the units of rate in the rate equation?
mol dm^-3 s^-1
How can you work out the units of k?
(mol dm^-3 s^-1)/((mol dm^-3)^m)(mol dm^-3)^n)
How do you work a value for k?
rate/[A]^m[B]^n
What does the order of reaction with respect to a reactant/catalyst tell you?
How the concentration of the reactant/catalyst affects the rate of reaction
What does zero order mean?
Changes to [A] has no effect on the rate of reaction
What does first order mean?
Rate ∝ [A]
If [A] doubles, rate of reaction doubles
What does second order mean?
Rate ∝ [A]^2
If [A] doubles, rate of reaction quadruples
Define ‘half-life of a reactant’
The time it takes for half the reactant to be used up
How can the order of reaction by worked out by looking at the shape of [reactant]-time graphs?
By seeing if the half-life is constant. If the half-life decreases as time goes on, it is zero order. It’s first order if the half-life remains constant. If the half-life increases, it’s second order
How can k be worked out from first order reaction graphs?
k=(ln2)/half life
