Q3.102P - Chemistry: Molecular Nature Of Matter And Change

Question

A sample of concentrated nitric acid has a density of 1.41 g/mL and contains 70.0% HNO₃ by mass. (a) What mass of HNO₃ is present per liter of solution? (b) What is the molarity of the solution?

Step-by-Step Solution

Answer

1. The mass of HNO₃ that is present per liter of the solution is 987 g HNO₃/L solution.
2. The molarity of the solution is 15.7 M HNO₃.

Step 1: Finding the mass of HNO 3 is present per liter of solution

a. The mass of theHNO₃can be expressed as:

$\begin{array}{rcl}Mass of HN{O}_3 (1 L solution)& =& \frac{1.41 g solution}{{10}^{-3} L solution}\times \frac{70 g HN{O}_3}{100 g solution}\\ & =& 987 g HN{O}_3/L solution.\end{array}$

Step 2: Finding molarity of the solution

b. Now, multiply the reciprocal of the molar mass to find the molarity

$\begin{array}{rcl}Molarity& =& \frac{987 g HN{O}_3}{L solution}\times \frac{mol HN{O}_3}{63.01 g HN{O}_3}\\ & =& 15.7 HN{O}_3.\end{array}$