Question

The density of nitric acid solution is 1.5 g mL\(^{-1}\). Its weight percentage is 68. What is the approximate concentration (in mol L\(^{-1}\)) of nitric acid? (N = 14 u; O = 16 u; H = 1 u)

• A. \( 14.2 \)
• B. \( 11.6 \)
• C. \( 18.2 \)
• D. \( 16.2 \)

Hint:

To determine molarity from weight percentage and density: 1. Multiply the density by 1000 to get total mass per liter. 2. Use the weight percentage to find the mass of solute. 3. Divide by the molecular weight to get molarity.

Answer 1

The Correct Option is D

Here's how to calculate the concentration:

1. Mass of nitric acid in 1 L of solution:
   Density = 1.5 g/mL = 1500 g/L
   Weight percentage of nitric acid = 68%
   Mass of nitric acid = (68/100) * 1500 g = 1020 g
2. Moles of nitric acid:
   Molar mass of \(HNO_3\) = 1 + 14 + (3 * 16) = 63 g/mol
   Moles of nitric acid = mass / molar mass = 1020 g / 63 g/mol = 16.19 mol
3. Concentration of nitric acid:
   Concentration = moles / volume = 16.19 mol / 1 L = 16.19 mol/L ≈ 16.2 mol/L

Therefore, the approximate concentration of nitric acid is 16.2 mol L^-1.