Question

At 25 °C, how many dissociated H ions are there in 355 mL of an aqueous solution whose pH is 11.67?

How can I do this if I cannot get the concentration of the solution?

Answer 1

the pH is a measure of concentration of H+, realated by the following

pH=-log₁₀([H+])

so

[H+]=10^-pH

[H+]=10^-11.67

[H+]=2.138x10^-12 mole/L

Now we convert conentration to amount using the volume

n=2.138x10^-12(mole/L)*.335 (L)*6.022x10²³ (molecules/mole)

n=4.313x10¹¹ ions

hope that helps