0.6140 grams of sodium phosphate (Na3PO4) was dissolved in 2 L of water to make a stock solution. 34 mL of this solution is then diluted to 100mL volumetrically to prepare the final solution. Calculate the molarity of phosphate ions in this solution. Answer to 5 decimal places.
To calculate the molarity of phosphate ions in the final solution, we need to consider the dilution that occurred when 34 mL of the stock solution was diluted to 100 mL.
Step 1: Calculate the moles of sodium phosphate in the stock solution.
Molar mass of Na3PO4 = 22.99 g/mol + (3 * 15.999 g/mol) + (4 * 31.00 g/mol) = 163.94 g/mol
Moles of Na3PO4 = mass / molar mass = 0.6140 g / 163.94 g/mol = 0.0037473 mol
Step 2: Calculate the moles of sodium phosphate in the final solution.
Since the stock solution was diluted to 100 mL volumetrically, the number of moles of sodium phosphate remains the same.
Moles of Na3PO4 in the final solution = 0.0037473 mol
Step 3: Calculate the molarity of phosphate ions in the final solution.
Since each molecule of sodium phosphate (Na3PO4) contains one phosphate ion (PO4), the molarity of phosphate ions is the same as the molarity of Na3PO4.
Volume of the final solution = 100 mL = 0.100 L
Molarity of phosphate ions in the final solution = Moles of Na3PO4 / Volume of the final solution
= 0.0037473 mol / 0.100 L = 0.037473 mol/L
Therefore, the molarity of phosphate ions in the final solution is 0.037473 mol/L (to five decimal places).
To calculate the molarity of phosphate ions in the final solution, we need to follow several steps:
Step 1: Convert the mass of sodium phosphate (Na3PO4) to moles.
First, we need to convert the mass of sodium phosphate to moles by dividing it by its molar mass.
The molar mass of Na3PO4 can be calculated as:
(3 x atomic mass of sodium) + (1 x atomic mass of phosphorus) + (4 x atomic mass of oxygen)
= (3 x 22.99 g/mol) + (1 x 30.97 g/mol) + (4 x 16.00 g/mol)
= 163.94 g/mol
Now, divide the given mass (0.6140 grams) by the molar mass of Na3PO4 to get moles:
moles of Na3PO4 = 0.6140 g / 163.94 g/mol
Step 2: Calculate the number of moles of phosphate ions (PO4-).
In sodium phosphate (Na3PO4), there is one phosphate ion for each Na3PO4 molecule. Therefore, the number of moles of phosphate ions is equal to the number of moles of sodium phosphate.
Step 3: Calculate the final volume of the solution in liters.
We diluted 34 mL of the stock solution to a final volume of 100 mL. To express the volume in liters, divide it by 1000:
final volume = 100 mL / 1000 mL/L
Step 4: Calculate the molarity of phosphate ions.
The molarity (M) is defined as moles of solute (phosphate ions) per liter of solution.
molarity of phosphate ions = moles of phosphate ions / final volume in liters
Now, let's put all the values into the equation and calculate the molarity of phosphate ions:
moles of Na3PO4 = 0.6140 g / 163.94 g/mol (from Step 1)
moles of phosphate ions = moles of Na3PO4
final volume = 100 mL / 1000 mL/L (from Step 3)
molarity of phosphate ions = moles of phosphate ions / final volume in liters
Now, you can input the values and calculate the molarity of phosphate ions.