How Fast? (Rates) 5.1.1

Question 1

What are the units of Rate?

Answer 1

mol dm^-3 s^-1

moles per decimeter cubed per second

Question 2

What is a Zero Order Reactant?

Answer 2

Where the rate is independent of the concentration of the reactant.
As a result does get shown in the rate equation

Question 3

What is a First Order Reactant?

Answer 3

Where the rate is directly proportional to the concentration of the reactant.
Is power of 1 in rate equation

Question 4

What is a Second Order Reactant?

Answer 4

Wher the rate is directly proportional to the concentration squared of the reactant.
is power of 2 in rate equation

Question 5

What shape are Concentration-Time graphs?

Answer 5

0th:
Straight line with negative gradient
1st:
Exponential decay, with a constant half life
2nd:
Decays faster than 1st and has no constantg half life

Question 6

What is the Gradient of a Concentration-Time graph?

Answer 6

Rate of reaction

Question 7

What shape are Rate-Concentration graphs?

Answer 7

0th:
Flat horizontal line (as doesn’t affect rate)
1st:
Positive gradient straight line (double con=double rate)
2nd:
Exponential growth (double con = quadruple rate)

Question 8

What is the Overall Order of Reaction?

Answer 8

The sum of the order of reaction

Question 9

What is the Rate equation?

Answer 9

Rate = k [A]^a [B]^b
k = Rate constant
a = Order with respect to A
b = Order with respect to B

Question 10

How is the units for Rate Constant found?

Answer 10

Reverse engineer it from the units within the rate equation

Question 11

What equation links Half Life and Rate Constant?

Answer 11

k = Ln(2) / Half life

Question 12

What is the Rate Determining Step?

Answer 12

RDS
The slowest step in a reaction.
(as several steps may occur with in a single reaction)

Question 13

How do you know what is in the RDS?

Answer 13

Its the reactants in the Rate equation.

As the RDS which affects the overall rate of reaction

Question 14

What is the Arrhenius Equation?

Answer 14

The equation which links rate constant and temperature
k = Ae^(-Ea/RT)
k = Rate Constant
A = Frequency/Pre-exponential Factor
Ea = Activation Energy
R = Gas Constant
T = Temperature (Kelvin)

Question 15

What is the Arrhenius Equation in Logarithmic form?

Answer 15

Lnk = (-Ea/R) x (1/T) + LnA

Question 16

How is the Arrehius Equation used to calculate the Activation Energy?

Answer 16

Lnk = (-Ea/R) x (1/T) + LnA
Is in the form y=mx+c
So (-Ea/R) = m
m is obtainable from a Lnk-1/tgraph