5.1 Flashcards
Define rate of reaction
The change in concentration of a reactant or a product per unit time
What is the rate equation?
k[A]¹[B]² = rate
Describe zero, first, and second order
Zero - rate is unaffected by changing the concentration
First - rate is directly proportional to the concentration
Second - the change in rate will be equal to the change in concentration squared
Zero order concentration-time graph
Straight line with concentration decreasing at a constant rate
First order concentration-time graph
Curved line with constant half-life (halving of reactant concentration at equal time intervals)
Zero order rate-concentration graph
Flat line, as the changes in concentration of the reactant have no effect on the rate
First order rate-concentration graph
Straight line through origin increasing with constant gradient.
Second order rate-concentration graph
Line curving upwards
Define rate-determining step
The slowest step in a multi-step reaction
Define order
The order with respect to a reactant is the power to which the concentration of the reactant is raised in the rate equation
Define the rate constant, k
The constant that links the rate of reaction with the concentrations of the reactants raised to the powers of their orders in the rate equation
Define half-life
The half-life of a reactant is the time take for the concentration of the reactant to reduce by half
Equation linking rate constant (k) and half life (t1/2)
k= ln 2/t1/2
How to process results from observation of precipitate forming (e.g. X obscured by cloudy solution)
Initial rate = 1/T
Plot a graph of 1/T against concentration
H2O2 + KI + H+
H2O2 + 2I- + 2H+ –> I2(aq) + 2H2O
I2 + Na2S2O3
2S2O3(2-) + I2 –> S4O6(2-) + 2I-
Define intermediate
An intermediate is a species formed in one step of a multi-step reaction that is used up in a subsequent step, and is not seen as either a reactant or a product of the overall reaction.
Define equivalence point
The equivalents point is, the point in a titration at which the volume of one solution has reacted exactly with the volume of the second solution.
How does the end point of a titration link with indicators?
The endpoint is the point in a titration at which there are equal concentrations of the weak acid and conjugate base forms of the indicator. The colour at the end point is midway between the colours of the acid and conjugate base forms.
