Question

What does 50,045 in the Alkalinity calculation formula, alkalinity = (Vol. of Acid x Normality of Acid x 50,045)/(vol. of sample ) mean and how is it derived?

Answer 1

We have such equation for titration:

$$N_1V_1 = N_2V_2$$

V is the consumed volume of solution, N is the solution normality:

$$N = c/z$$

where z is change in oxidation state for red-ox titrations, amount of available proton or hydroxide ions for acid-base titrations and so on.

$$c = n/V = \frac{m/M}{V}, \text{ hence } N = c/z = \frac{m}{M/z \cdot V}$$ $$\frac{m}{V} = \frac{N_2V_2}{V_1} \cdot \frac{M}{z}$$

The value m/V can be called alkalinity of the solution in grams. So your value seemed to be the equivalent molar mass of your alkali M/z.