Question

GIVEN A SOLUTION OF 70WT% NITRIC ACID (HNO3), HOW MUCH SOLUTION IS NEEDED TO CREATE A 1L OF 3M SOLUTION OF NITRIC ACID (HNO3)?

Answer 1

molarity = (number of mole)/(volume in L)
3 = (number of mole)/1
number of mole = 3
also,
number of mole = (given mass)/(molar mass)
molar mass of HNO3 = 63 g/mol
3 = (given mass)/63
given mass = (3*63) g
given mass = 189 g

now, 70% of HNO3 means
70 g of HNO3 is present in 100 g of solution
1 g of HNO3 is present in (100/70) g of solution
189 g of HNO3 is present in (100/70)*189 g of solution
189 g of HNO3 is present in 270 g of solution
amount of solution required = 270 g

Answer : 270 g