Question

calculate the concentration of nitric acid in moles per litre in a sample which has density 1.40 g/ml and the mass percent of nitric acid in it being 69%.​

Answer 1

15.44 M

Given:

Density of Nitric Acid = 1.40 g/ml

Percentage of Nitric Acid that is present in the solution = 69 %

To Find:

Molarity of the solution / Concentration of Nitric Acid in soln.

Solving:

Formula used to find the mass of Nitric Acid in the solution :

Mass of HNO3 = Density x Mass Percent of HNO3

Substituting the values into this formula and calculating the Mass of HNO3:

= 1.41 g/ml x 69%  

= 0.9729 g/ml  

Finding the quantity in terms of Mole:

= Mass of HNO3 / Molar Mass of HNO3

Calculating the molar mass of HNO3:

= 1 x 1 + 14 x 1 + 16 x 3

= 1 + 14 + 48

= 15 + 48

= 63 g/mol

Calculating the moles by using the formula mentioned above:

= 0.9729 g/ml / 63 g/mol

= 0.01544 mol/ml

Converting the mole obtained into liters we get:

For converting into liter we multiply the mole obtained x 1000

= 0.01544 x 1000

= 15.44 M

Therefore, the concentration of nitric acid in moles per litre in the sample is 15.44 M.

Answer 2

Answer:

Question:-

Calculate the concentration of nitric acid in moles per litre in a sample having density 1.41gm / ltr ,mass percent of nitric acid being 69%. In other words, find Molarity (M) ?

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Answer:-

Concentration in moles per litre = Molarity (M) = (No. of moles of solute) / (Volume of solution in litres)

And No. of moles of solute = (Mass of solute) / (Molecular Mass of solute)

So,

Molarity = (Mass of solute) / [ Molecular mass of solute * Volume of solution of litres ]

Given: 100% of the sample has 69% HNO₃ by mass

=> 100g of the sample has 69g of HNO₃

So, Mass of solute = 69g

and Mass of Solution = 100g

Molecular mass of HNO₃ :-

= 1 + 14 + (16 * 3) g/mol

= 63 g/mol

So, Molecular mass of solute = 63 g/mol

Volume of solution :-

(Mass of solution) / (Density of Solution)

= (100g) / (1.41 g/ml)

= 70.92 ml

We have to convert ml to litres

= 70.92 * (10)^(-3) l

So,

Molarity = (Mass of solute) / [ Molecular mass of solute * Volume of solution of litres ]

= (69) / (63 * 70.92 * (10)^(-3) M

= 15.44 M

(M stabds for molar)

Ans. Molarity = 15.44 M