As we know,
pH + pOH = 14
Or,
pOH = 14 - pH
Putting Value of pH,
pOH = 14 - 10.62
pOH = 3.38
pOH is converted into [OH⁻] as follow,
[OH⁻] = 10⁻pOH ∴ -pOH is in power, 10 means antilog
press shift and click log button
[OH⁻] = 10⁻³°³⁸
[OH⁻] = 0.0004168
[OH⁻] = 4.16 × 10⁻⁴
<span>Which of the following pairs of compounds would you expect to form homogeneous solutions when combined?
</span><span>a) CH3CH2CH2CH2CH3 AND CH3CH2CH2CH2CH2CH3
and
</span><span>c) LiNO3 and H2O</span>
Explanation:
The given reaction is as follows.

Hence, number of moles of NaOH are as follows.
n = 
= 0.005 mol
After the addition of 25 ml of base, the pH of a solution is 3.62. Hence, moles of NaOH is 25 ml base are as follows.
n = 
= 0.0025 mol
According to ICE table,

Initial: 0.005 mol 0.0025 mol 0 0
Change: -0.0025 mol -0.0025 mol +0.0025 mol
Equibm: 0.0025 mol 0 0.0025 mol
Hence, concentrations of HA and NaA are calculated as follows.
[HA] = 
[NaA] = 
![[A^{-}] = [NaA] = \frac{0.0025 mol}{V}](https://tex.z-dn.net/?f=%5BA%5E%7B-%7D%5D%20%3D%20%5BNaA%5D%20%3D%20%5Cfrac%7B0.0025%20mol%7D%7BV%7D)
Now, we will calculate the
value as follows.
pH = 
![pK_{a} = pH - log \frac{[A^{-}]}{[HA]}](https://tex.z-dn.net/?f=pK_%7Ba%7D%20%3D%20pH%20-%20log%20%5Cfrac%7B%5BA%5E%7B-%7D%5D%7D%7B%5BHA%5D%7D)
= 
= 3.42
Thus, we can conclude that
of the weak acid is 3.42.
To convert from moles to grams you divide by the molar mass of the element. To convert from grams to moles you X by the molar mass element