# Tutorial 4: Hydrolysis Of Aspirin Flashcards Preview

## PHARM202 Labs > Tutorial 4: Hydrolysis Of Aspirin > Flashcards

Flashcards in Tutorial 4: Hydrolysis Of Aspirin Deck (13)
0
Q

Why is the solution buffered?

A

So that the hydroxyl ion concentration remains constant. We can then rewrite the rate constant as -dA/dt = KappA

1
Q

What rate of reaction is aspirin hydrolysis? Why?

A

The reaction is second order because it is dependent on the concentration and the solution pH

2
Q

What will the degradation of aspirin buffered at pH7 ([OH] constant) then follow?

A

First order kinetics, where the rate of reaction, k is only dependent on the concentration of one reactant

3
Q

What is the effect of pH on the hydrolysis of aspirin?

A

Aspirin hydrolyses in acid and base

Increased pH will increase hydrolysis

4
Q

What is the effect of temperature on the hydrolysis of aspirin?

A

Increased temperature can increase the reaction rate

5
Q

Describe the hydrolysis and stability of aspirin at different pH values

A

At pH 4 aspirin is most stable
Between pH 5-7: its decomposition is independent of pH
Above pH 10: the decomposition rate rapidly increases

6
Q

What is shelf life?

A

The length of time required for the product potency to be reduced to some percentage of its original value

The time at which the product content is reducated to 90% of its original potency

7
Q

Why is shelf life important?

A

It is desirable to determine the stability of the active ingredient in the drug so that a shelf life or expiration date may be assigned to the product

8
Q

What are the components and their units of the Arrhenius equation?

A

Kapp: this is the apparent rate constant.
0 order (mol/L/min)
1st order: min-1
2nd order: L/mol/min

```α = frequency constant
Ea= activation energy (kj/mol)
R = gas constant (1.987cal/mol/K or 8.314J/mol/K)
T = temperature (K)```
9
Q

What is the activation energy?

A

The minimum energy required for a chemical reaction to proceed

There must be sufficient number of molecules with energy equal or higher than Ea

10
Q

What is the rearranged equation for activation energy?

A

lnKapp = lnα-Ea/RT

11
Q

What is the rate constant?

A

The speed of the chemical reaction