٠ا Ù٠اÙرÙ٠اÙÙÙدرÙجÙÙÙ – Ù ÙÙاس اÙأس اÙÙÙدرÙجÙÙÙ
تعتبر ØÙ Ùضة ÙÙÙÙÙØ© اÙÙ ØÙÙÙ Ù ÙÙ Ø© ÙÙغاÙØ© Ù٠٠عاÙجة اÙÙ Ùا٠باÙتÙØ§Ø¶Ø Ø§ÙعÙس٠بسبب عÙا٠٠٠ث٠تدÙÙر اÙغشاء Ø ÙتÙظÙ٠اÙأغشÙØ© Ø Ù٠ا Ø¥ÙÙ Ø°ÙÙ. ÙØ°ÙÙ Ùأ٠بعض اÙتÙاعÙات اÙÙÙÙ ÙائÙØ© ستØدث ÙÙØ· عÙد Ù ÙÙاس أس ÙÙدرÙجÙÙÙ Ù Øددة.
Ùستخد٠اÙ٠صطÙØ Ø§Ùأس اÙÙÙدرÙجÙÙÙ ÙÙص٠٠ا إذا Ùا٠اÙÙ ØÙÙÙ ÙÙÙ٠أ٠Øا٠ضÙ. Ø£Ùض٠Ùص٠ÙÙ ÙÙÙ٠اÙØÙ Ùضة ÙاÙÙÙÙÙØ© Ù٠اÙعÙدة Ø¥Ù٠ثابت اÙتÙÙÙ.
باÙÙظر Ø¥Ù٠اÙأس اÙÙÙدرÙجÙÙÙ ØÙ٠ترÙÙز اÙÙÙدرÙجÙÙ H + ion Ø Ùر٠أÙ٠٠ع ارتÙاع ترÙÙز H + (ÙÙÙ٠ترÙÙز OH) ÙØص٠عÙ٠رÙ٠سÙب٠أصغر. ÙباÙÙ Ø«Ù Ø Ù Ø¹ ارتÙاع ترÙÙز اÙÙÙدرÙÙسÙد (ÙÙÙ٠ترÙÙز H +) ÙØص٠عÙ٠رÙ٠سÙب٠أÙبر.
[H +] x [OH-] = 1.0 x 10 ^ -14
Ù
ع إضاÙØ© اÙØÙ
ض (H +)
1.0 x 10 ^ -5 x 1.0 x 10 ^ -9 = 1.0 x 10 ^ -14
Ù
ع إضاÙØ© اÙÙاعدة (OH-)
1.0 x 10 ^ -9 x 1.0 x 10 ^ -5 = 1.0 x 10 ^ -14
تغÙÙرات اÙأس اÙÙÙدرÙجÙÙ٠٠ع اÙتغÙرات ÙÙ H + ÙترÙÙزات OH
٠ع أخذ Ø°ÙÙ Ù٠اÙاعتبار Ø Ø¹Ù٠اÙعÙ٠اء أ٠طرÙÙØ© Ø£Ùثر Ù Ùاء٠ة ÙÙص٠ترÙÙز Ø£ÙÙ٠اÙÙÙدرÙجÙÙ Ù٠اÙÙ ØÙÙÙ Ù٠أخذ اÙÙÙغارÙت٠اÙساÙب ÙترÙÙز Ø£ÙÙÙات اÙÙÙدرÙجÙÙ. اÙÙÙغارÙØ«Ù Ù٠اÙأس اÙÙÙدرÙجÙÙ٠اÙØ°Ù Ùت٠رÙع رÙ٠أساس Ù ÙÙ ÙØ¥Ùتاج رÙ٠٠عÙÙ. Ù ÙاØظة: سÙستخد٠عادة Ùاعدة Ù Ù 10.
٠ثاÙ: اÙسج٠(اÙÙÙغارÙت٠) Ù Ù 100 ÙÙ 2: عشرة ٠رÙÙع Ø¥ÙÙ ÙÙØ© 2 (102).
٠ثاÙ: سج٠127 ÙÙ 2.1 (عÙ٠اÙØ¢ÙØ© اÙØاسبة اÙعÙÙ ÙØ© Ø Ø£Ø¯Ø®Ù 127 Ø Ø«Ù Ø§Ø¶ØºØ· اÙÙ ÙØªØ§Ø [LOG]).
رÙÙ | ÙÙغارÙت٠| رÙÙ | ÙÙغارÙت٠|
1 = 1 X 10^0 | 0 | 1.0 = 1 X 10^0 | 0 |
10 = 1 X 10^1 | 1 | 0.1 = 1 X 10^-1 | -1 |
100 = 1 X 10^2 | 2 | 0.01 = 1 X 10^-2 | -2 |
1000 = 1 X 10^3 | 3 | 0.001 = 1 X 10^-3 | -3 |
10000 = 1 X 10^4 | 4 | 0.0001 = 1 X 10^-4 | -4 |
100000 = 1 X 10^5 | 5 | 0.00001 = 1 X 10^-5 | -5 |
1000000 = 1 X 10^6 | 6 | 0.000001 = 1 X 10^-6 | -6 |
10000000 = 1 X 10^7 | 7 | 0.0000001 = 1 X 10^-7 | -7 |
ر٠ز اÙسج٠اÙساÙب ÙÙ “p”. ÙØ°ÙÙ Ø Ùإ٠اÙسج٠اÙسÙب٠ÙترÙÙز Ø£ÙÙ٠اÙÙÙدرÙجÙÙ ÙÙ “Ù ÙÙاس اÙأس اÙÙÙدرÙجÙÙÙ”. Ùسرد اÙجدÙ٠أدÙا٠اÙعدÙد ٠٠ترÙÙزات Ø£ÙÙÙات اÙÙÙدرÙجÙÙ ÙترÙÙزات ÙÙدرÙÙسÙد Ùدرجة اÙØÙ Ùضة اÙÙ ÙابÙØ© Ù pOH. ÙاØظ أ٠اÙرÙ٠اÙÙÙدرÙجÙÙÙ 7 Ù ØاÙدة Ùأ٠ترÙÙز Ø£ÙÙ٠اÙÙÙدرÙجÙÙ [H +] ÙترÙÙز اÙÙÙدرÙÙسÙد [OH-] Ù٠ا ÙÙس اÙØ´ÙØ¡. Ù٠ا ÙزÙد [H +] Ø ÙÙÙص اÙأس اÙÙÙدرÙجÙÙÙ.
H+ (mol/L) | OH- (mol/L) | ||||
عدد عشر٠| SN | pH | عدد عشر٠| SN | pOH |
0.00000000000001 | 1 X 10^-14 | 14 | 1.0 | 1 X 10^0 | 0 |
0.0000000000001 | 1 X 10^-13 | 13 | 0.1 | 1 X 10^-1 | 1 |
0.000000000001 | 1 X 10^-12 | 12 | 0.01 | 1 X 10^-2 | 2 |
0.00000000001 | 1 X 10^-11 | 11 | 0.001 | 1 X 10^-3 | 3 |
0.0000000001 | 1 X 10^-10 | 10 | 0.0001 | 1 X 10^-4 | 4 |
0.000000001 | 1 X 10^-9 | 9 | 0.00001 | 1 X 10^-5 | 5 |
0.00000001 | 1 X 10^-8 | 8 | 0.000001 | 1 X 10^-6 | 6 |
0.0000001 | 1 X 10^-7 | 7 | 0.0000001 | 1 X 10^-7 | 7 |
0.000001 | 1 X 10^-6 | 6 | 0.00000001 | 1 X 10^-8 | 8 |
0.00001 | 1 X 10^-5 | 5 | 0.000000001 | 1 X 10^-9 | 9 |
0.0001 | 1 X 10^-4 | 4 | 0.0000000001 | 1 X 10^-10 | 10 |
0.001 | 1 X 10^-3 | 3 | 0.00000000001 | 1 X 10^-11 | 11 |
0.01 | 1 X 10^-2 | 2 | 0.000000000001 | 1 X 10^-12 | 12 |
0.1 | 1 X 10^-1 | 1 | 0.0000000000001 | 1 X 10^-13 | 13 |
1.0 | 1 X 10^-0 | 0 | 0.00000000000001 | 1 X 10^-14 | 14 |
- Published in Water Chemistry, Water Treatment
What is pH – pH Scale Definition
pH refers to the concentration of hydrogen ions in solution. The lower the pH the more hydrogen
ions present. The higher the pH the fewer hydrogen ions present
The acidity and alkalinity of a solution is extremely important in Reverse Osmosis water treatment due to factors such as membrane degradation, membrane cleaning, etc. This is because certain chemical reactions will only take place at specific pH values.
The term pH is used to describe whether a solution is alkaline or acidic. The concept of acidity and alkalinity may best be described by going back to the dissociation constant.
Looking at the exponent on the concentration of Hydrogen H+ ion, we see that as the H+ concentration goes up (and OH- concentration goes down) we get a smaller negative number. Likewise, as Hydroxide OH- concentration goes up (and H+ concentration goes down) we get a larger negative number.
[H+] x [OH-] = 1.0 x 10^-14
With addition of acid (H+)
1.0 x 10^-5 x 1.0 x 10^-9 = 1.0 x 10^-14
With addition of base (OH-)
1.0 x 10^-9 x 1.0 x 10^-5 = 1.0 x 10^-14
Exponent changes with changes in H+ and OH- concentrations
Taking this into consideration, scientists learned that a more convenient way to describe the hydrogen ion concentration of a solution is to take the negative logarithm of the hydrogen ion concentration. A logarithm is the exponent to which a base number is raised to produce a given number. NOTE: We will usually use a base of 10.
EXAMPLE: The log (logarithm) of 100 is 2: Ten raised to the power of 2 (102).
EXAMPLE: The log of 127 is 2.1 (On a scientific calculator, enter 127, then push the [LOG] key).
NUMBER | LOG | NUMBER | LOG |
1 = 1 X 10^0 | 0 | 1.0 = 1 X 10^0 | 0 |
10 = 1 X 10^1 | 1 | 0.1 = 1 X 10^-1 | -1 |
100 = 1 X 10^2 | 2 | 0.01 = 1 X 10^-2 | -2 |
1000 = 1 X 10^3 | 3 | 0.001 = 1 X 10^-3 | -3 |
10000 = 1 X 10^4 | 4 | 0.0001 = 1 X 10^-4 | -4 |
100000 = 1 X 10^5 | 5 | 0.00001 = 1 X 10^-5 | -5 |
1000000 = 1 X 10^6 | 6 | 0.000001 = 1 X 10^-6 | -6 |
10000000 = 1 X 10^7 | 7 | 0.0000001 = 1 X 10^-7 | -7 |
The symbol for the negative log is “p”. Therefore, the negative log of the Hydrogen ion concentration is “pH”. Table below lists several hydrogen ion concentrations, hydroxide concentrations, and the corresponding pH and pOH. Note that a pH of 7 is neutral because the Hydrogen ion concentration [H+] and hydroxide concentration [OH-] are the same. As [H+] increases, pH decreases.
H+ (mol/L) | OH- (mol/L) | ||||
Decimal | SN | pH | Decimal | SN | pOH |
0.00000000000001 | 1 X 10^-14 | 14 | 1.0 | 1 X 10^0 | 0 |
0.0000000000001 | 1 X 10^-13 | 13 | 0.1 | 1 X 10^-1 | 1 |
0.000000000001 | 1 X 10^-12 | 12 | 0.01 | 1 X 10^-2 | 2 |
0.00000000001 | 1 X 10^-11 | 11 | 0.001 | 1 X 10^-3 | 3 |
0.0000000001 | 1 X 10^-10 | 10 | 0.0001 | 1 X 10^-4 | 4 |
0.000000001 | 1 X 10^-9 | 9 | 0.00001 | 1 X 10^-5 | 5 |
0.00000001 | 1 X 10^-8 | 8 | 0.000001 | 1 X 10^-6 | 6 |
0.0000001 | 1 X 10^-7 | 7 | 0.0000001 | 1 X 10^-7 | 7 |
0.000001 | 1 X 10^-6 | 6 | 0.00000001 | 1 X 10^-8 | 8 |
0.00001 | 1 X 10^-5 | 5 | 0.000000001 | 1 X 10^-9 | 9 |
0.0001 | 1 X 10^-4 | 4 | 0.0000000001 | 1 X 10^-10 | 10 |
0.001 | 1 X 10^-3 | 3 | 0.00000000001 | 1 X 10^-11 | 11 |
0.01 | 1 X 10^-2 | 2 | 0.000000000001 | 1 X 10^-12 | 12 |
0.1 | 1 X 10^-1 | 1 | 0.0000000000001 | 1 X 10^-13 | 13 |
1.0 | 1 X 10^-0 | 0 | 0.00000000000001 | 1 X 10^-14 | 14 |
- Published in Water Chemistry, Water Treatment