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Help 3. Find the pH of a solution in which 500.ml of 0.20 M NiH.Cl s pK, (NHe)-9

ID: 304253 • Letter: H

Question

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3. Find the pH of a solution in which 500.ml of 0.20 M NiH.Cl s pK, (NHe)-9.25 titrated with 0.10 mol HNO pK. (HNO,)-1.4 4. Find the pH of a solution when 120 g of NaOH is added to 3.0 L of 0.75 M HF. Assume no change in volume. pK, (HF)-3.17 pH a S. Find the p? of a solution when 100. mL of 0.60 M HC,H,0, is combined with 100. ml. of 0.07 M NaC,HO pK. (HC2H,02)-4.76 6. Find the pH of the solution if 15 g of NaNO, is added to 300. ml of 0.10 M HNO2. Assume no change in volume. pK, (HNO:) 3.40 pH - 7. Find the pH of a solution in which 1.25 L of 0.50 M NaCIO, and 0.75 L of 0.80 Mare combined. followed by 0.30 mol of HCL pK, (HCIO:) 1.96 pK, (HCI)-7

Explanation / Answer

3) HNO3 is strong acid,NH4Cl weakly acidic.so that, acidity depends majorly on HNO3

concentration of HNO3 = n/v = 0.1/0.5 = 0.2 M

pH = -log(H3O+)

     = -log(0.2)

     = 0.7

4) No of mol of HF taken = M*V

               = 0.75*3

               = 2.25 mol

No of mol of NaOH = 120/40 =   3 mol

so that, total HF reactes with NaOH.and some extra NaOH is left in the mixture.

pH depends on extra NaOH

concentration of extra NaOH = n/v = (3-2.25)/3 = 0.25 M

pOH = - log(OH-)

     = -log0.25

     = 0.6

pH = 14-0.6 = 13.4

5) No of mol of CH3COOH = 0.1*0.6 = 0.06 mol

   No of mol of CH3COONa = 0.1*0.07 = 0.007 mol

pH = pka + log(CH3COONa/CH3COOH)

pka of ch3cooh = 4.76

pH = 4.76+log(0.007/0.06) = 3.83

6) No of mol of NaNO2 = 15/69 = 0.217 mol

   No of mol of HNO2 = 0.3*0.1 = 0.03 mol

pka of HNO2 = 3.4

pH = 3.4+log(0.217/0.03) = 4.26

7) No of mol of HClO2 = 0.75*0.8 = 0.6 mol

   No of mol of nAcLo2 = 1.25*0.5 = 0.625 mol

   PKA OF hcLo2 = 1.96

   pH = pka + log(NaClO2-HCl)/(HClO2+HCl)

      = 1.96+log((0.625-0.3)/(0.6+0.3))

      = 1.52