Average burette reading = Volume of NaOH solution (V1) =
4.5+4.5+4.4+4.4+4.4
5
=4.44mL Strength of NaOH solution =S1(M)( say )=S1(N) Volume of oxalic acid solution (V2)=10mL Strength of oxalic acid solution (S2)=1.25M =1.25×2N So, V1S1=V2S2 ( ∵ Law of equivalence) ⇒S1=
V2S2
V1
=
10×(1.25×2)
4.44
=5.63N ∼eq6M=6M Note n-factor of NaOH=1 n-factor of H2C2O4=2 (oxalic acid) N=M×n