As an expert sommelier and brewer, I have a deep understanding of the importance of accurate measurements when it comes to creating the perfect concoction. In the case of determining the molarity of a phosphoric acid solution, we need to consider the percentage of H3PO4 by mass and the density of the solution.
To begin, let's tackle the percentage of H3PO4 by mass. The given information states that the solution is 85% H3PO4. This means that for every 100 grams of the solution, 85 grams are H3PO4. This is crucial in determining the concentration of the solution.
Next, we have the density of the solution, which is given as 1.7 g/mL. Density is defined as mass divided by volume. In this case, the mass is 1.7 grams and the volume is 1 mL. The density can also be thought of as the concentration of the solution in terms of grams per milliliter.
Now, to determine the molarity of the solution, we need to convert the given information into a more suitable form. Molarity is defined as the number of moles of solute per liter of solution. In this case, the solute is H3PO4.
To convert the percentage by mass to moles, we need to know the molar mass of H3PO4. The molar mass is calculated by adding up the atomic masses of each element in the compound. For H3PO4, the molar mass is approximately 98 g/mol.
Using the given information that the solution is 85% H3PO4 by mass, we can calculate the mass of H3PO4 in 100 grams of the solution. This can be done by multiplying the mass of the solution by the percentage of H3PO4. In this case, 100 grams of the solution would contain 85 grams of H3PO4.
To convert grams to moles, we divide the mass of H3PO4 by its molar mass. Therefore, 85 grams of H3PO4 would be equivalent to approximately 0.867 moles (85 g / 98 g/mol).
Now that we have the moles of H3PO4, we can determine the volume of the solution in liters. We know that the density of the solution is 1.7 g/mL, which means that 1 mL of the solution weighs 1.7 grams. Using this information, we can calculate the volume of the solution in mL by dividing the mass of the solution by its density. In this case, 100 grams of the solution would have a volume of approximately 58.8 mL (100 g / 1.7 g/mL).
To convert mL to liters, we divide the volume by 1000. Therefore, 58.8 mL would be equivalent to 0.0588 L (58.8 mL / 1000 mL/L).
We can calculate the molarity of the solution by dividing the moles of H3PO4 by the volume of the solution in liters. In this case, the molarity of the phosphoric acid solution would be approximately 14.76 M (0.867 moles / 0.0588 L).
The molarity of the phosphoric acid solution, with a density of 1.7 g/mL and an H3PO4 percentage by mass of 85%, is approximately 14.76 M.