Darwinbots Forum

General => Off Topic => Topic started by: Zelos on October 17, 2005, 09:49:05 AM

Title: Solvity in water
Post by: Zelos on October 17, 2005, 09:49:05 AM

I found how much H+/OH- ions water can keep at certain temperatures, but im trying to fix a formula that have a error of max 10% at every value. anyone can figure it out? here is the list: (I use PH differens from normal (24°C), at 24°C its 14 with pH+ and pOH- values togather)
0 = -0,943095
5 = -0,730487
10 = -0,533132
15 = -0,344862
20 = -0,166853
24 = 0
30 = 0,1676127
35 = 0,3197305
40 = 0,4647875
50 = 0,7384634
60 = 0,9238655
100 = 1,710117

anyone knows a program or something that can comeup with that kind of formula?

Title: Solvity in water
Post by: Griz on October 17, 2005, 11:50:43 AM

no doubt you'll have to factor in varying density ...
interesting that it is 0 at 24C. :huh:
I wonder how/why we came to consider 20C/68F to be SOT?

~griz~

Title: Solvity in water
Post by: Zelos on October 17, 2005, 12:47:54 PM

ots 0 cause ive logarithmed the change, and the change is 1. like 1*X, and lg 1 = 0 so thats why its 0. so you just take 14+the change. like 24° 14+0=14
the 14 value is (pOH +pH) and that is constant aslongest you dont change the tmp.

Title: Solvity in water
Post by: Numsgil on October 17, 2005, 01:35:47 PM

Correct me if I'm wrong, but can't water contain indefinate numbers of said ions?  Since said ions are directly related to pH, and pH doesn't have an upper or lower bound.

Title: Solvity in water
Post by: Zelos on October 17, 2005, 01:39:06 PM

not really, but maybe ur right in the english part. but im really talking about pH+pOH and it have a certain value at each temperature

Title: Solvity in water
Post by: Numsgil on October 17, 2005, 01:49:54 PM

Anyway, for the math part:

A TI-83 (standard graphing calculator) could do this no sweat.

Title: Solvity in water
Post by: PurpleYouko on October 17, 2005, 02:21:23 PM

Zelos. Where did you get these numbers from? If you are trending pH against temperature then your scale goes the wrong way.

As temperature increases, pH decreases. It looks like you are showing it the other way around unless I'm reading your post wrong