[النمر المتوحش]

يا جماااعة لو سمحتوا مين يقدر يبسط لي الحل لاني ما فهمت له

You have 20.0 mL of a solution of a weak
acid, HX, whose Ka 5 2.14 3 10
26
. The pH of
the solution is found to be 3.800. How much
distilled water would you have to add to the
solution to increase the pH to 4.000?
Original solution:
[H1
] 5 antilog(2pH) 5 antilog (23.800)
5 1.58 3 10
24
[H1
][X2
_]
[HX]
5
(1.58 3 10
24
)
2
__
Minitial
5 2.14 3 10
26
Minitial 5
(1.58 3 10
24
)
2
__
(2.14 3 10
26
)
5 0.0117M
Diluted solution:
[H1
] 5 antilog(2pH) 5 antilog (24.000)
5 1.00 3 10
24
2.14 3 10
26 >
(1.00 3 10
24
)
2
__
Mfinal

Mfinal 5
(1.00 3 10
24
)
2
__
2.14 3 10
26
5 0.00467M
Moles of HX in the initial and final solutions are
equal.
(Minitial
)(Vinitial
) 5 (Mfinall
)(Vfinal
)
(0.0117M 3 20.00 mL) 5 (0.00467M 3 Vfinal
)
Vfinal 5
(0.0117 mol/L) (20.00 mL) ___
0.00467 mol/L

Add 30.1 mL of distilled water to the original