How to Calculate Mole Fraction of Nitric Acid in Concentrated Solution
What is the mole fraction of nitric acid in a concentrated solution?
Given that concentrated nitric acid is 70.4% HNO3 by mass in 2.0 moles of water, how do we determine the mole fraction of nitric acid?
Calculation of Mole Fraction
Concentrated nitric acid is 70.4% HNO3 by mass, which means the remaining mass is water. To calculate the mole fraction of nitric acid, we first need to find the moles of nitric acid.
Given that the mass of the solution is 70.4 g and the molar mass of HNO3 is 63.01 g/mol:
Number of moles of HNO3 = mass / molar mass = 70.4 g / 63.01 g/mol = 1.11 mol
Next, we need to find the total moles in the solution (HNO3 + H2O):
Total moles = 1.11 mol (HNO3) + 2.0 mol (H2O) = 3.11 mol
Finally, we can calculate the mole fraction of nitric acid:
Mole fraction of HNO3 = moles of HNO3 / total moles = 1.11 mol / 3.11 mol ≈ 0.357
Understanding Mole Fraction
Mole fraction is a way to express the concentration of a component in a mixture. It is defined as the ratio of the number of moles of a specific component to the total number of moles in the mixture.
In the case of concentrated nitric acid solution, the mole fraction of HNO3 tells us the proportion of nitric acid molecules compared to all molecules present in the solution. In this scenario, the mole fraction of HNO3 is approximately 0.357, indicating that nitric acid molecules make up around 35.7% of the total moles in the solution.
By understanding and calculating mole fractions, we can gain insights into the composition and concentration of various components in a mixture, aiding us in chemical analysis and solution preparation.