Question

Calculate the pH of the following solutions: (a) 10-3 M HClO4 (note that for HClO4 the pKa = -7) (b) 10-3 M HOCl (note that for HOCl the pKa =7.52) (x) 10-6.5 M NaOH (d) 10-3 M NH4Cl (note that for NH4+ the pKa =9.25)

Answer 1

PART (a):

• HClO₄ ------> H⁺ + ClO₄^-

Concentration of H⁺ is given by:

Therefore, pH is given by:

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PART (b):

• HOCl ------> H⁺ + OCl^-

Concentration of H⁺ is given by:

Therefore, pH is given by:

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PART (c):

• NaOH -----> Na⁺ + OH^-

Hence, Concentration of OH^-, [OH^-] = 10^-6.5 M

Therefore, pH is given by:

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PART (d):

• NH₄⁺ + H₂O ------> NH₃+ H₃O⁺

Concentration of H⁺ is given by:

Therefore, pH is given by:

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