What is the pOH of a solution prepared by dissolving 0.835 g of KOH(s) in 7.70 L of water?
A.2.714
B.1.827
C.7.000
D.11.286
E.12.173
Molar mass of KOH = 1*MM(K) + 1*MM(O) + 1*MM(H)
= 1*39.1 + 1*16.0 + 1*1.008
= 56.108 g/mol
mass of KOH = 0.835 g
we have below equation to be used:
number of mol of KOH,
n = mass of KOH/molar mass of KOH
=(0.835 g)/(56.108 g/mol)
= 1.488*10^-2 mol
volume , V = 7.70 L
we have below equation to be used:
Molarity,
M = number of mol / volume in L
= 1.488*10^-2/7.7
= 1.933*10^-3 M
[OH-] = [KOH] = 1.933*10^-3 M
we have below equation to be used:
pOH = -log [OH-]
= -log (1.933*10^-3)
= 2.714
Answer: A
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