How do you calculate pH and Ka values with just concentration?

I have 50ml NaOH at 0.1mol and 50ml of HCl at 0.1mol.

I titrated to find the range of the mid-point colour change. The indicator is of unknown quantity, concentration and pH%26lt;5.



Is it possible to calculate the exact pH of the mid-point colour change? Bearing in mind the change was between pH 8.9 and 1.6

Is it possible to calculate Ka values?How do you calculate pH and Ka values with just concentration?
A) NaOH and HCL are strong electrolytes.



B) Indicator is for it's nature a weak acid or base, his amount has to be very small



It's impossible to reconiza optically the exact mid point because eye has not the sensibility to reconize the colour change in the exact pH point of the pH range of mid-point.