How Many Grams of 70% Concentrated Nitric Acid Are Required to Prepare 250 mL of 2.0 M HNO3

When preparing laboratory-grade solutions, understanding the concentration and molarity of your reactants is crucial. In this guide, we will walk through the calculation needed to determine the amount of 70% concentrated nitric acid (HNO3) required to prepare 250 mL of a 2.0 M HNO3 solution.

Understanding the Problem

Our objective is to prepare a solution with a specific concentration and volume. The requirement is to prepare 250 mL of a 2.0 M HNO3 solution. This means that we need to determine how much of the 70% concentrated nitric acid should be used. Here’s a step-by-step guide on how to achieve this.

Steps Involved in the Calculation

Step 1: Calculate the Number of Moles of HNO3 Required

We start by using the molarity equation to calculate the number of moles of HNO3 needed:

molarity (M) moles of solute / volume of solution in liters

Rearranging the formula, we find:

moles of solute molarity times; volume(L)

For a 2.0 M solution and a volume of 250 mL (0.250 L):

moles of HNO3 2.0 M times; 0.250 L 0.50 moles

Step 2: Calculate the Mass of HNO3 Needed

Next, we need to determine the mass of nitric acid required. The molar mass of HNO3 is approximately 63.01 g/mol. Thus, the mass can be calculated as follows:

mass of HNO3 moles times; molar mass

mass of HNO3 0.50 moles times; 63.01 g/mol 31.505 g

Step 3: Determine the Mass of Concentrated Solution Needed

Since the concentrated nitric acid solution is 70% HNO3 by mass, we use the following equation:

mass of concentrated solution mass of HNO3 / percentage of HNO3

mass of concentrated solution 31.505 g / 0.70 ≈ 45 g

Therefore, you would need approximately 45 grams of the 70% concentrated nitric acid solution to prepare 250 mL of a 2.0 M HNO3 solution.

Conclusion

When preparing concentrated acid solutions like nitric acid, it is essential to take necessary safety measures, such as wearing appropriate safety equipment and following proper laboratory procedures. This ensures the safety of the personnel and prevents accidents during the preparation and handling of the solution.

Following these steps, you can accurately prepare the desired concentration of nitric acid in solutions for various laboratory applications.