Q.1 calculate the pH of a 0.158 Ca(CIO)2. Q.2 An aqueous solution of HCl is 2.67
ID: 929574 • Letter: Q
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Q.1 calculate the pH of a 0.158 Ca(CIO)2. Q.2 An aqueous solution of HCl is 2.67 m (molality). What is the molarity of the HCl solution. The molar mass of HCl is 36.461 g/mol and the density of the solution is 1.095 g/mL. Q.1 calculate the pH of a 0.158 Ca(CIO)2. Q.2 An aqueous solution of HCl is 2.67 m (molality). What is the molarity of the HCl solution. The molar mass of HCl is 36.461 g/mol and the density of the solution is 1.095 g/mL. Q.2 An aqueous solution of HCl is 2.67 m (molality). What is the molarity of the HCl solution. The molar mass of HCl is 36.461 g/mol and the density of the solution is 1.095 g/mL.Explanation / Answer
Since HClO is a weak acid, it forms easily in aqueous solutions, in effect, it will also form OH- (ClO- + H2O --> HClO + OH-). In this case, we need to use the Kb since it forms OH- instead of H+. To get Kb, just divide 10 ^-14 by Ka.
let Ka for HClO = 3.5 x 10^-8
Kb = 2.86 x 10^-7 [since Kb>Ka, soln is basic]
[OH-] is defined by the relation Kb = [OH-][HClO]/[ClO-]. [OH]=[HClO]. Assuming the equilibrium conc of ClO- doesn't change significantly, [OH-]= sqrt(Kb*0.158*2) [since there are 2 moles of ClO for every mole of Ca(ClO)2].
[OH-] = 3.00 x 10^-4
pOH = 3.52
pH= 14- pOH
pH = 10.47
2) 2.67 moles in 1 kg of solution = 2.67 m
volume of 1 kg ( 1000 g) = 913.24 ml
mass of HCl = 2.67 mol x 36.461 g/mol = 97.35 g
molarity = 2.67 mol/ 0.91324 L = 2.9236 M
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