buffer solution

o岩o岩個2個人係完全錯ga......
我o岩o岩學buffer solution.
如果put water in the pH meter, it will affect the pH meter when it's measuring something else because the water will react with whatever in pH meter.
A buffer solution do not affect the pH of the solution because it got the conjugate base/acid of the solution that is being test with.
Acid + Water = (H+) + A {HA = H+ + A}
Base + Water = (OH-) + B {HB = OH- + B}

For example: HC2H3O2 + H2O = H+ + C2H3O2

if it's a buffer solution, there is already some C2H3O2 in the solution in the beginning.

HC2H3O2 + H2O = H+ + C2H3O2
Initial 1M 0M 0M 0.5M
Change -X +X +X
Equilibrium -X+1 X X+0.5

if there's C2H3O2 in the solution in the beginning, there will be a lot less H+ being made and so the pH of the solution will only change by a very small ammount

因為水唔係neutral ga.....
而buffer soluions 就可以clean up some
and turn it bk to neutral...
hope it helps.....

2007-03-22 07:43:19 補充：
i think danny one is much betteruse his

coz the pH of water is not necessarily 7.... therefore buffer solution (usually have a pH of 7) is used-->more accurate