Question #7aa1b
1 Answer
See explanation.
Explanation:
I'm not really sure what you're asking here, so I'll just do a quick breakdown of how the pH of a solution is calculated.
As you know, the pH of the solution is simply a measure of the concentration of hydronium ions,
More specifically, the pH of a solution is calculated by taking the negative log base 10 from the concentration of hydronium ions.
color(blue)("pH" = - log(["H"_3"O"^(+)])pH=−log([H3O+])
You need to take the negative log of the concentration because you're dealing with concentrations that are are, in most cases, smaller than
log(x) < 0" " (AA) color(white)(a) 0 < x < 1log(x)<0 (∀)a0<x<1
You know that the molarity of the hydronium ions is equal to
"pH" = - log(0.2) = - (-0.699) = 0.7pH=−log(0.2)=−(−0.699)=0.7
You can find the concentration of hydronium ions by using the fact that
10^(log_10(x)) = x10log10(x)=x
So if you start with
"pH" = 0.7pH=0.7
you can say that
overbrace(-log(["H"_3"O"^(+)]))^(color(purple)(="pH")) = 0.7
log(["H"_3"O"^(+)]) = - 0.7
Since you can say that if
10^log(["H"_3"O"^(+)]) = 10^(-0.7)
This will get you
["H"_3"O"^(+)] = 10^(-0.7) = 0.1995 = 0.2
