Final answer:
To calculate the average mass of citric acid per 2L bottle of soda, determine the number of moles of citric acid, by dividing its mass by the molar mass, and then calculate the molarity. If multiple bottles are being averaged, sum the masses of citric acid and divide by the number of bottles. For mole fraction, calculate moles of citric acid and water separately and divide moles of citric acid by the total moles.
Step-by-step explanation:
To find the average mass of citric acid per 2L bottle of soda, you'll need to first determine the number of moles of citric acid present in the soda. You can do this by obtaining the mass of citric acid present in a sample and dividing it by the molar mass of citric acid. Once you have the number of moles, you can calculate the molarity by dividing the moles of citric acid by the volume of the solution in liters. Instead of acetic acid, we're interested in citric acid for this question, but the concept is the same.
For example, if a 2L bottle of soda contains 10 grams of citric acid, and the molar mass of citric acid is approximately 192.12 g/mol, the moles of citric acid would be 10 g / 192.12 g/mol = 0.0521 mol. You can then divide these moles by the total volume of soda to get the molarity, which in this case would be 0.0521 mol / 2 L = 0.0260 M. To find the average mass, if you have multiple bottles, add up all the masses and then divide by the number of bottles.
In a case where you need to find the mole fraction, you could first calculate the mass of water in the soda and then determine the number of moles of water. To calculate the mole fraction of citric acid, divide the number of moles of citric acid by the sum of the number of moles of citric acid and the number of moles of water.