How to calculate the molarity of phosphoric aci9d in a solution that is 84% by mass phosphoric acid and a density of 1.87 g/ml

84% by mass H3PO4 means 84 g H3PO4 in 100 g solution. M = moles/L.

How many moles are in 84g H3PO4? That is 84/molar mass H3PO4.
What is the volume of 100 g soln.
mass = volume x density. You know mass and density, solve for volume.
Then M = #moles/L

To calculate the molarity of phosphoric acid in the given solution, you will need to follow these steps:

Step 1: Determine the molar mass of phosphoric acid (H₃PO₄).
The molar mass of phosphoric acid is calculated by summing up the atomic masses of each element:
Molar mass of H = 1.01 g/mol
Molar mass of P = 30.97 g/mol
Molar mass of O = 16.00 g/mol
So, the molar mass of H₃PO₄ = (3 * 1.01) + 30.97 + (4 * 16.00) = 98.00 g/mol

Step 2: Calculate the mass of phosphoric acid in the solution.
Given that the solution is 84% by mass phosphoric acid and has a density of 1.87 g/ml, we can use the following formula:
Mass = Volume * Density
Assuming we have 100 ml of the solution, the mass of the solution would be:
Mass = 100 ml * 1.87 g/ml = 187 g

To find the mass of phosphoric acid in the solution, we multiply the total mass of the solution by the weight percent of the acid:
Mass of phosphoric acid = 0.84 * 187 g = 157.08 g

Step 3: Calculate the number of moles of phosphoric acid.
To find the number of moles, divide the mass of phosphoric acid in grams by the molar mass:
Moles of phosphoric acid = Mass of phosphoric acid / Molar mass of phosphoric acid
Moles of phosphoric acid = 157.08 g / 98.00 g/mol = 1.60 mol

Step 4: Calculate the volume of the solution.
Since we are given the density of the solution, we can calculate the volume using the formula:
Volume = Mass / Density
Volume = 187 g / 1.87 g/ml = 100 ml

Step 5: Calculate the molarity of the phosphoric acid.
Molarity is defined as moles of solute per liter of solution. In this case, the solute is phosphoric acid and the volume used is in liters:
Molarity of phosphoric acid = Moles of phosphoric acid / Volume of solution in liters
Molarity of phosphoric acid = 1.60 mol / 0.1 L = 16 M

Therefore, the molarity of phosphoric acid in the given solution is 16 M.

To calculate the molarity of phosphoric acid in the given solution, you'll need to follow these steps:

Step 1: Find the mass of phosphoric acid in the solution.
Given that the solution is 84% by mass phosphoric acid, it means that 100 g of the solution contains 84 g of phosphoric acid. Let's assume you have 100 mL of the solution (since the density is given as 1.87 g/mL). Hence, the mass of the solution is 100 mL * 1.87 g/mL = 187 g. Therefore, the mass of phosphoric acid is 84% of 187 g = 0.84 * 187 g = 157.08 g.

Step 2: Determine the molar mass of phosphoric acid.
Phosphoric acid (H3PO4) consists of one phosphorus (P) atom, three hydrogen (H) atoms, and four oxygen (O) atoms. The atomic masses are: P = 31.0 g/mol, H = 1.0 g/mol, and O = 16.0 g/mol. To calculate the molar mass of phosphoric acid, add up the masses of each atom in one molecule: (3 * 1.0 g/mol) + (1 * 31.0 g/mol) + (4 * 16.0 g/mol) = 98.0 g/mol.

Step 3: Calculate the number of moles of phosphoric acid.
The number of moles (n) can be calculated using the formula: n = mass (in grams) / molar mass (in grams per mole). In this case, the mass of phosphoric acid is 157.08 g (from Step 1) and the molar mass is 98.0 g/mol (from Step 2). Hence, the number of moles of phosphoric acid is: n = 157.08 g / 98.0 g/mol = 1.601 moles.

Step 4: Determine the volume of the solution in liters.
Since the solution's density is given as 1.87 g/mL, it means that 1 mL of the solution has a mass of 1.87 g. Therefore, for a mass of 187 g (as determined in Step 1), the volume of the solution is 187 g / 1.87 g/mL = 100 mL = 0.1 L.

Step 5: Calculate the molarity (M) of the phosphoric acid.
The molarity is defined as moles of solute per liter of solution. In this case, the number of moles (from Step 3) is 1.601 moles and the volume of the solution (from Step 4) is 0.1 L. Hence, the molarity of phosphoric acid is: M = 1.601 moles / 0.1 L = 16.01 M.

Therefore, the molarity of phosphoric acid in the given solution is 16.01 M.