N.B. Using one of the hypertext links within this test may occasionally cause answers already entered to be cleared. Please check and re-enter the answers if necessary. This problem will only occur if caching is not in operation for your Web browser.

You will need a scientific calculator for this test. If you have not brought your calculator with you, don't worry you may be able to run one on your computer.
For example, if you are using a PC running Windows 3.x then

1. Hold down the 'Alt' key and press the 'Tab' key until 'Program Manager' appears in the box at the centre of the screen.
2. Realease the 'Alt' key.
3. Double click on the Calculator icon in the Accessories Group.
4. If necessary use view|scientific to obtain the the scientific version of the calculator.
5. Use Alt and Tab as before to return to your Web browser.
6. You can now use Alt and Tab to use the calculator when required.

If you are using a different system, equivalent procedures may well be available.

The following expressions may be derived for the percentage ionization of acids and bases at a given pH.

These equations will be required in subsequent questions.
You will be able to scroll back up to them if you need to check.

Ephedrine is a basic drug with a pKa of 9.6
Calculate the percentage ionization of ephedrine in blood plasma pH 7.4

0.7
0.6
99.4
99.3

Paracetamol is an acidic drug with pKa 9.5
Calculate the percentage ionization of paracetamol in blood pH 7.4

0.7
99.3
0.8
99.2

Suprofen is an acidic drug with pKa = 3.9
What would be the %ionization in the stomach (pH 1).

0.13
99.98
99.87
0.02

Suprofen is an acidic drug with pKa = 3.9
What would be the %ionization in the blood plasma (pH 7.4)

0.75
99.25
99.98
0.02

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