Question

how many gram of NIOS are present in 5 litre of its 0.1M

Answer 1

pH= 7 means the product is neutral, thus by the concept of Law Of Equivalencewe can find out the the needed weight for NaOH

Gram equivalents of NaOH= Gram Equivalents of HCl to get resulting product neutral.

Thus, formula goes like:

{[Required weight * n-factor of NaOH]/molar mass of NaOH}={[Normality of HCl*given Volume]/1000}

***(Normality=n-factor * Molarity)

Putting values:

Step 1: {[X(Required weight)*1]/40}={[0.5*400]/1000}

Step 2: X/40=200/1000

Step 3: X={[200*40]/1000}

Step 4: X= 8 grams of NaOH

Thus, 8 Grams of NaOH is required to be added to 400 mL of aqueous HCl sol. of 0.5 Molarity to get  pH of resulting solution as 7.

Hope this will help...