I noticed that after distillation by minipore machine pH of water increases around 8.5-9. But I don't know why it increase and its stability. Is it needed to maintain to 7,mainly for germination of seed.
ask minipore to check integrity of menbranes and soda traces. You may calibrate your pH meter by using another water and phosphate buffer at http://www.unl.edu/cahoonlab/phosphate%20buffer.pdf If pH of your water is still above 7 after calibration stop using the minipore. I guess that the problem arises from the use of an old ion exchanger resin
obviously there is something wrong with your procedure. Something got dissolved to make pH > 7 or your pH measurement is faulty.
There should be a contamination somewhere, It is obvious no 100% elimination of ions by distillation owing to the octahedral stature of water molecules but ion effects is ignorable
Syed,
CO2 dissolved in distilled water can increase pH turning into H2CO3. With ratio [НСО3-]/[СО2] =100, рН = 8,5. But, this is upper limit for pH due to high concentration of CO2.
Check your pH-meter and water source before your Millipore.
The only way to change the pH of distilled water is contact with atmosphere. This way CO2 enters the distilled water in accordance with Henry's low. CO2 (s) forms H2CO3 which dissociates .
And if my friend Alex will excuse me!.., this reduces the pH of the water all the way down to around 5.5. Check the dissociation constant of the weak acid H2 CO3. This is an easy test for students as well.
In essence, contact with atmosphere will introduce a weak acid into distilled water
ask minipore to check integrity of menbranes and soda traces. You may calibrate your pH meter by using another water and phosphate buffer at http://www.unl.edu/cahoonlab/phosphate%20buffer.pdf If pH of your water is still above 7 after calibration stop using the minipore. I guess that the problem arises from the use of an old ion exchanger resin
Calibrate the pH meter several times check the pH of Millipore water and again happens inform the Millipore to check it . The storage bottle and the Contact with atmosphere may introduce change in the pH of distilled water
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