Question

a solution is rotulated as 0.0603% by mass in HClO4. the density of this silution us 1.00g/mL. the HClO4 has a molar mass of 100.5g/mol

express and calculate the cincentration has molarity of HClO4:_______M

complete the hydrolysis of HClO4: HClO4 + H2O ---->

calculate the concentration of H3O+_______M

the pH of the solution is:

Answer 1

--> Let mass of solution is 100 gram.

Volume of solution = mass/density

= 100/1.00 = 100 ml = 0.1 L

Mass of HClO4 = 100*(0.0603/100) = 0.0603 gram

Moles of HClO4 = mass/molar mass

= 0.0603/100.5

= 0.0006 mole

Concentration of HClO4 = moles/volume(L)

= 0.0006/0.1

= 0.006 M

--> hydrolysis of HClO4,

HClO4 + H2O --> H3O+ + ClO4-

--> from here we can see,

[HClO4] = [H3O+] = 0.006 M

--> pH = -log[H3O+] = -log(0.006) = 2.22

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