50ml of 0.2m HCL is added to 30ml of 0.1m KOH solution, find the pH of the solution?

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Answer

Calculation of pH of the Solution

Step 1: Write the Balanced Chemical Equation

HCl + KOH → KCl + H2O

Step 2: Calculate the Moles of HCl and KOH

Number of moles of HCl = Molarity × Volume of HCl = 0.2 × 0.05 = 0.01 moles

Number of moles of KOH = Molarity × Volume of KOH = 0.1 × 0.03 = 0.003 moles

Step 3: Determine the Limiting Reagent

KOH is the limiting reagent because it is present in lesser amount.

Step 4: Calculate the Moles of Excess HCl

Moles of HCl remaining after reaction = Moles of HCl added – Moles of KOH reacted

Moles of HCl remaining after reaction = 0.01 – 0.003 = 0.007 moles

Step 5: Calculate the Concentration of HCl

Concentration of HCl = Moles of HCl remaining/Total volume of solution

Concentration of HCl = 0.007/0.08 = 0.0875 M

Step 6: Calculate the pH of the Solution

pH = -log[H+]

[H+] = Concentration of HCl

pH = -log(0.0875)

pH = 1.06

Step 7: Conclusion

The pH of the solution is 1.06. The solution is highly acidic due to the presence of excess HCl.

Answer