Calculating the Percent by Mass of Nitric Acid in a Mixture
How to determine the percent by mass of nitric acid in a given mixture?
A 12.0 g sample of an aqueous solution of nitric acid contains an unknown amount of the acid. If 15.4 mL of 0.771 M sodium hydroxide are required to neutralize the nitric acid, what is the percent by mass of nitric acid in the mixture?
Calculating the Percent by Mass of Nitric Acid
To find the percent by mass of nitric acid in the mixture, we need to calculate the number of moles of nitric acid and then convert it to mass. First, we can use the given information to calculate the number of moles of sodium hydroxide used in the reaction:
Moles of NaOH = concentration × volume
Moles of NaOH = 0.771 M × 0.0154 L = 0.0119 mol
Since the reaction between nitric acid and sodium hydroxide occurs in a 1:1 ratio, the moles of nitric acid is also 0.0119 mol. The molar mass of nitric acid is 63.01 g/mol, so the mass of nitric acid in the mixture is:
Mass of nitric acid = moles of nitric acid × molar mass
Mass of nitric acid = 0.0119 mol × 63.01 g/mol = 0.75 g
To calculate the percent by mass, we divide the mass of nitric acid by the mass of the mixture and multiply by 100:
Percent by mass of nitric acid = (0.75 g / 12.0 g) × 100 = 6.25%
Calculating the percent by mass of nitric acid in a given mixture involves understanding the stoichiometry of the reaction between nitric acid and sodium hydroxide. By determining the moles of each substance involved and using their molar masses, we can calculate the mass percent of nitric acid in the solution.
In this scenario, the reaction between nitric acid and sodium hydroxide occurs in a 1:1 ratio, which simplifies the calculation process. By calculating the moles of sodium hydroxide used in the reaction, we can determine the moles of nitric acid present in the mixture as well.
By converting the moles of nitric acid to mass using its molar mass, we find that the mass of nitric acid in the mixture is 0.75 grams. Dividing this mass by the total mass of the mixture (12.0 grams) and multiplying by 100 gives us the percent by mass of nitric acid, which is 6.25% in this case.
Understanding how to calculate percent by mass in chemical solutions is important for various applications in chemistry, such as determining the concentration of substances in mixtures or solutions. By following the steps outlined in this example, you can accurately calculate the percent by mass of nitric acid in a given mixture.