explain how you know???
2007-08-27 11:09:52 · 4 answers · asked by sweetlilme17 2 in Science & Mathematics ➔ Chemistry
A pH 2 solution is slightly greater than 10,000 times more acidic than a pH 6 solution since pH is strictly the log of the hydrogen ion activity, not the log of the hydrogen ion concentration. Activity is related to concentration through activity coefficients, which tend to decrease from unity with increasing ionic strength (at infinite dilution, the activity coefficient of a solute is unity). As pH decreases below seven for water not containing any ions other than the counter ion for the acid, ionic strength increases, so activity of the hydrogen ion decreases and it takes a few more hydrogen ions in solution to get the same change in terms of pH units as at a higher pH. Therefore, the actual concentration of acid at pH 2 is slightly more than 10,000 times the concentration of the acid at pH 6.
Anyone who says 10,000 times for a pH change of four units would fail a graduate aquatic chemistry exam if the prof were being picky, and they are always being picky in graduate school.
2007-08-27 19:15:17 · answer #1 · answered by gcnp58 7 · 0⤊ 0⤋
The basis behind this question deals with the logarithmic scaling of the pH scale. The equation for pH is:
--- pH = -log[H3O+]
Since the pH scale is logarithmic, the pH changes by 1 unit when [H3O]+ (hydrogen ion concentration) changes by a factor of 10; the pH changes by 2 units when the [H3O]+ changes by a factor of 100; and the pH changes by 6 units when [H3O]+ changes by a factor of 1,000,000.
--There is a difference of 4 units between a pH 2 and a pH 6. For each of the four units there is a 10 times difference in hydrogen ion concentration.
-From the equation: pH = -log(H+) the answer to your problem can be solved. All you need to do is take the inverse log of 4:
10^4 = 10,0000
A solution with a pH of 2 is 10,000 times more acidic than a solution with a pH of 6.
2007-08-27 18:31:07 · answer #2 · answered by madscientist 3 · 0⤊ 1⤋
The pH scale is logarithmic, meaning that each pH unit is actually 10 times more acidic. So, pH 5 is 10 times more acidic than pH6; pH 4 is 100x, pH 3 is 1000X, and pH 2 is 10,000x more acidic than pH 6.
2007-08-27 18:18:35 · answer #3 · answered by Mike R 2 · 1⤊ 0⤋
pH = -log[¨H+| rearrange and find the H+ concentration for each pH. you will find how many times the H+ concentration is higher for pH2 than for pH6.
2007-08-27 18:18:49 · answer #4 · answered by Manuelon 4 · 0⤊ 0⤋