Question

How many grams of concentrated nitric acid solution should be used to prepare 250mL of 2.0M HNO3 ?The concentrated acid is 70% HNO3.

Answer 1

Given,

Mass of whole solution = 100 g
Then,

Mass of HNO3 = 70 g

Volume of solution = 250 ml

Molarity = Moles of solute / Volume of solution *1000

2.0 M = ( Moles of HNO3 / 250) * 1000

Moles of HNO3 = 2.0 /4

MOLES OF HNO3 = 0.5

Moles of HNO3 = Mass of HNO3 / Molar Mass of HNO3

Mass of HNO3 = 0.5 * 63 = 32.5 gm

32.5 g of HNO3 is present in ( 100 * 31.5 / 70

Mass of HNO3 required = 45 g.