Question

When you are making your 0.1 M NaOH, why do you not have to know exactly how much water you add to the stock sodium hydroxide solution? ( in this experiment we have to dilute 0.5 M NaOH to 500 mL 0.1M)

Answer 1

Because NaOH is hygroscopic in nature. It absorb moisture and some acidic compounds (like CO₂) from the atmosphere, as a result the nomality of the stock solution is not same ie. 0.5 M.

So to prepare 500 mL of 0.1 M NaOH solution , first we have to find the exact molarity of 0.5 M NaOH stock solution a

then use Molarity eqaution, M1V1= M2V2

So first step is the standardization of 0.5 M NaOH