We have the given reaction as;
---->
<span>
Answer A) The pH will be 12.36,</span>
<span>We have to convert the concentrations of HCl and NaOH into moles,</span>
So we have, n(HCl) =
(0.0290 L) X (0.290 mol/L) = 8.41X moles <span>
and for NaOH we have, n(NaOH) = (0.0390 L)(0.290 mol/L) =
1.13X moles
Now, it seems NaOH is in excess, so amount remaining will be;
1.13 X - 8.41 X
= 2.89
X
moles
<span>Now, the total volume will become as = 0.0390 + 0.0290 = 0.068 L </span>
So, the concentration of [] = 2.89×10ˉ³ mol
/ 0.068 L = 4.25 X
M
pOH = - log [] = -log (4.25×
)
= 1.37
Hence, pH = 14 - pOH = 14 - 1.37 = 12.6</span>
So the pH of the
solution will be 12.6 which is basic in nature. <span>
Answer B) The pH will be 1.68 </span>
<span>Now, for the given concentration we need to find moles for HCl and NaOH also;</span>
n(HCl) = (0.0290
L)(0.290 mol/L) = 8.41 X mol <span>
<span>n(NaOH) = (0.0190 L)(0.390 mol/L) = 7.41 X mol </span>
here we can see, HCl is in excess amount so the remaining
will be;
8.41X - 7.41 X
= 1.0 X
mol
Here, the total volume will be = 0.0290 + 0.0190 = 0.0480 L
So the concentration of [HCl] = 1.0 X mol
/ 0.0480 L = 2.08 X
M </span>
Which is = [H⁺] <span>
So, the pH = - log [] = -log(2.08X
)
= 1.68</span>
Hence, the pH will be 1.63 which is more acidic in nature.
