1) According to the law of chemical equivalance, "Substances reacts completely with each other in the equal no of their gram equivalents.|"

       i.e  No. of of gram equiv. of one substance = no. of gram equiv. of another substance.

2) At equivalence point, normality equation holds true. 

    i.e      N1V1=N2V2

3) Concentration of solution is inversely proportional to dilution.

eg. 100 cc of 1N solution = (100*10) cc of N/10 solution.

      x ml of y N solution = (x*y) ml of 1N solution.

4) Equal strength of solution neutralize in equal volume.

eg. 10 ml of 1 N NaoH = 10 mo of 1N HCl

       1000 ml of 1N HCl = 1 gm equiv. of NaoH

5) For the mixture of acid or bases:

N1V1+N2V2+................+ Nn*Vn = Nm*Vm

where Nm= normality of resulting solution.

and Vm= total volume of mixture.

6) For the mixture of acid and Bases:-

Na*Va - Nb*Vb = Nm*Vm

if Nm is +ve then resulting solution is acidic.

if Nm is -ve then resulting solution is basic. and if Nm=0 then the solution is neutral.