Answer:
A. 11.26
B. 12.37
Explanation:
A. Step 1:
Dissociation of Mg(OH)2. This is illustrated below below:
Mg(OH)2 <==> Mg2+ + 2OH-
A. Step 2:
Determination of the concentration of the OH-
From the above equation,
1 mole of Mg(OH)2 produce 2 moles of OH-
Therefore, 9.01x10^-4 M Mg(OH)2 will produce = 9.01x10^-4 x 2 = 1.802x10^-3 M of OH-
A. Step 3:
Determination of the pOH. This is illustrated below:
pOH = - Log [OH-]
[OH-] = 1.802x10^-3 M
pOH = - Log [OH-]
pOH = - Log 1.802x10^-3
pOH = 2.74
A. Step 4:
Determination of the pH.
pH + pOH = 14
pOH = 2.74
pH + 2.74 = 14
Collect like terms
pH = 14 - 2.74
pH = 11.26
B. Step 1:
Dissociation of NH4OH. This is illustrated below below:
NH4OH <==> NH4+ + OH-
B. Step 2:
Determination of the concentration of the OH-
From the above equation,
1 mole of NH4OH produce 1 moles of OH-
Therefore, 2.33x10^-2M of NH4OH will also produce 2.33x10^-2M of OH-
B. Step 3:
Determination of the pOH. This is illustrated below:
pOH = - Log [OH-]
[OH-] = 2.33x10^-2M
pOH = - Log [OH-]
pOH = - Log 2.33x10^-2M
pOH = 1.63
B. Step 4:
Determination of the pH.
pH + pOH = 14
pOH = 1.63
pH + 1.63 = 14
Collect like terms
pH = 14 - 1.63
pH = 12.37
