Calling all smart people....

[geekgrl]

I did an experiment to calculate the rate of reaction for a chemical equation with varying temps, etc.
I am calculating the concentration of my iodine by multiplying the molarity (0.2) * the volume, and then dividing by the total volume. Then, I am trying to take the ln (natural log) of that concentration.
My ln is coming out to be negative, and for some reason I am thinking that I can't have a negative ln. Can or can't I? And if it cannot be negative, what is going wrong?!?!

Thanks

[Martoch]

So what you're saying is that if we don't know the answer we're not smart???


Dangit I thought I was smart!!!
WAAAAAAAAAHHHH!!!!!


Good luck with that one...of course I know the answer already, I just want to let you ponder it a little longer.

[geekgrl]

LOL no.
I'm smart but I don't know the answer

I am just thinking that a natural log is supposed to be positive so I must have a mistake somewhere. I just don't know how or why.

[willy_ph]

If I remember correctly, I think there can be a negative rate of reaction. I think that it is positive if the reaction releases heat and negative if it pulls heat in from the surrounding area.

Don't quote me on that. I don't remember much from chemistry...I'm taking political science and philosophy.

[Martoch]

I didn't look this up or anything, it just hit me while I was browing through my laboratory.

You can only take the log of positive numbers: If x is negative or zero, you CAN'T take the log of x -- not the natural log or the log of any base. In addition, the base of a log must also be positive.

Natural log is positive or negative depending upon whether x is greater than or less than 1: If x > 1, then ln(x) > 0. If x < 1, then ln(x) < 0. If x = 1 then ln(x) = 0. Indeed the log to any base of 1 is always zero.

Clear as mud? I just confused myself...

[daveleau]

Isn't Theophylact a chemist? I bet he would know off the top of his head. I have plenty of chem textbooks, but would have to dig them out. As for the ln question, this link : http://www.wikipedia.org/wiki/Natural_logarithm states that ln is a positive real number. Hence, there's got to be an error somewhere... Finding it;s the hard part. Sorry I couldn't be of more help...

[geekgrl]

Thanks guys.
You all have helped me to conclude that I have a major error!!

Now - where to find it in my ~400 data points.