Which of the following solutions will have pH equal to 1.0?
55 mL of M10 HCl + 45 mL of M10 NaOH
50 mL of M5 HCl + 50 mL of M5 NaOH
75 mL of M5 HCl + 25 mL of M5 NaOH
None of the above
The correct option is C 75 mL of M5 HCl + 25 mL of M5 NaOH
We need to calculate the resulting molar concentration of H+ ions to determine the resulting pH of solutions. Here n-factor of NaOH and HCl is 1 . So Molarity and Normality are equal. Formula used is: Mmix=M1V1−M2V2V1+V2ifM1V1>M2V2 Option A: (0.1×55)>(0.1×45)Nmix=(0.1×55)−(0.1×45)100=0.01pH=−log(0.01)=2×log(10)=2
Option B: Since the concentration and volume of both NaOHandHCl is equal. It forms a neutral solution of pH=7