Question

Isotonic sodium chloride solution contains 0.9% w/v sodium chloride. If the E-value of boric acid is 0.52, calculate the percentage strength (w/v) of an isotonic solution of boric acid.

Answer 1

If the E-value of boric acid is 0.52 it means that 1g of boric acid contains 0.52g of NaCl.

Isotonic sodium chloride solution contains 0.9%w/v sodium chloride and we have to calculate the%strength of an isotonic solution of boric acid. Let us consider 0.9% as 0.9g dissolved in 100 ml and taking 0.9% simply as 0.9g. We just need to calculate how much boric acid is required which contain 0.9g of NaCl.

Hence, 1g boric acid/0.52g NaCl = x g boric acid/0.9g NaCl

x = 0.9/0.52

x = 1.73g

Now by converting it into %strength term we get 1.73% w/v