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# logP values watch

1. sorry if this should be more off a biology question

anyway from a lab measuring concentration of sulphonamide in a aqueous solution by UV spectroscopy for a calibration curve

we have determined experimentally the P value for each drug need to start with calculate the log P value

wondering how to go about this, if using a calculator which button would it be, or how you go about working it out?

thank you
2. log P simply means the power to which you raise the number 10 to get P.

ie: The log of 100 is 2, since if you raise 10 the power of 2, you get 100.

There should be a "log" button on your calculator. Or maybe a log button with a subscript 10.
3. (Original post by KiraMayz)
log P simply means the power to which you raise the number 10 to get P.

ie: The log of 100 is 2, since if you raise 10 the power of 2, you get 100.

There should be a "log" button on your calculator. Or maybe a log button with a subscript 10.
i should off known that

but how do i know what the power should be?
4. (Original post by Caspa)
i should off known that

but how do i know what the power should be?

The power is what you need to calculate.
5. (Original post by KiraMayz)

The power is what you need to calculate.
sorry i got confused, wonder how do i know what the power is?

i'm not too sure what it is for my case of results
6. (Original post by Caspa)
sorry i got confused, wonder how do i know what the power is?

i'm not too sure what it is for my case of results
Taking x as the power :
a^x = n
therefore :

log{a}(n} = x

a will be base 10 by default on your calculator.
7. I'm assuming P is what you measure. So P can have any value...right?

So, for example, in your experiment if you found the value of P to be 100, you want to find the value of log 100...right?

In the following two equations, x is what you are trying to find, as obviously x is the value of log P.

= x

is the same as:

= P

This is just a bit of maths. If you don't get it, just press the log button on your calculator followed by the value of P you measured and press the equals key
8. i am guessing that the absorbance would be the P value

so say p is 0.230
it would just be log 0.230

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