Question

calculate the concentration of nitric acid in moles per litre in a sample which has a density,1.41gm/L and the mass percentage of nitric acid in it being 69%.

Answer 1

Hey there!


Mass percent of HNO3=69%

Hence mass of HNO3 in the solution is 69g

Mass of water=100-69=31g

Number of moles of HNO3=69/63=1.09moles

Density=mass/volume

Volume=mass/density

  =100/1.41=70.9ml

 

Concentration (Molarity) = number of moles of solute/volume of the solution

   = (1.09/70.9)×100

  = 1.5M

 

Hope it helped!☺️

Answer 2

Mass percentage of Nitric acid = 69%
that means
69 g of pure Nitric acid in 100g of solution.

Density = Mass / Volume
Therefore,
Volume = Mass / Density
= 100/ 1.41 = 71 ml = 0.071 litre

Now, number of moles of Nitric acid
= given mass / Molar mass
= 69 / 63
= 23/21
= 1.09 mol

So,
Molarity = No.of moles of solute / Volume of solution
= 1.09 / 0.071
= 1.5 mol/litre.

Hope this helps you !!
#Dhruvsh