Answer:
2.4
Step-by-step explanation:
Step 1:
Data obtained from the question. This includes the following:
Mass of KOH = 0.655g
Volume of H2O = 3L
pOH =..?
Step 2:
Determination of the number of mole of KOH. This is illustrated below:
Mass of KOH = 0.655g
Molar mass of KOH = 39 + 16 + 1 = 56g/mol
Number of mole KOH =..?
Mole = Mass /Molar Mass
Number of mole of KOH = 0.655/56
Number of mole of KOH = 0.012 mol
Step 3:
Determination of the molarity of KOH.
The molarity of KOH can be obtained as follow:
Mole of KOH = 0.012 mol
Volume of water = 3L
Molarity =..?
Molarity = mole /Volume
Molarity of KOH = 0.012/3
Molarity of KOH = 4x10^–3 M
Step 4:
Determination of the concentration of Hydroxide ion, [OH-] in 4x10^–3 M KOH.
This can be obtained as follow:
The dissociation equation of KOH is given below:
KOH —> K+ + OH-
From the balanced equation above,
1 mole of KOH produced 1 mole of OH-.
Therefore, 4x10^–3 M KOH will also produce 4x10^–3 M OH-
The concentration of Hydroxide ion, [OH-] = 4x10^–3 M
Step 5:
Determination of the pOH of the solution.
pOH = –Log [OH-]
[OH-] = 4x10^–3 M
pOH = –Log 4x10^–3
pOH = 2.4
Therefore, the pOH of the solution is 2.4