Question

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

• A. 45.0 g conc. $HN{O}_3$
• B. 90.0 g conc. $HN{O}_3$
• C. 70.0 conc. $HN{O}_3$
• D. 54.0 g conc. $HN{O}_3$

Answer 1

The correct option is A 45.0 g conc. $HN{O}_3$

Moles of HNO${}^{{}_3}$ to be prepared = Molarity x Volume (L)

= 2.0 x 0.25

= 0.5 moles

$\therefore$ Mass of HNO${}_3$ to be prepared = 0.5 x 63 = 31.5 g

But the concentrated acid is 70% HNO${}_3$

Therefore, Mass of concentrated nitric acid solution required = $\frac{31.5g}{70}\times 100$

45 g conc of HNO${}_3$

Hence, the correct option is $A$