Final answer:
The concentration of Na in the solution is 0.401 M (molarity), 8.943 ppt (parts per thousand), and after dilution it becomes 92.25 ppm (parts per million).
Step-by-step explanation:
To calculate the concentration of sodium (Na) in a solution where 3.2473 g of Na2CrO4 is dissolved in 100.0 mL of water, you need to follow these steps:
- Determine the moles of Na2CrO4 by dividing the mass of Na2CrO4 by its molar mass:
Moles of Na2CrO4 = 3.2473 g / 161.97 g/mol = 0.02005 mol
- Calculate the total moles of Na, noting that each mole of Na2CrO4 contains 2 moles of Na:
Moles of Na = 0.02005 mol Na2CrO4 × 2 mol Na/mol Na2CrO4 = 0.0401 mol
- Convert the volume of the solution to liters and calculate the molarity (M):
Molarity = Moles of Na / Volume (L) = 0.0401 mol / 0.100 L = 0.401 M
- To find the concentration in parts per thousand (ppt), we first convert grams to milligrams:
Concentration of Na = (Mass of Na / Mass of solution) × 1000 ppt = (0.0401 mol × 22.9898 g/mol) / (100.0 mL × 1.00 g/mL) × 1000 ppt = 8.943 ppt
- For the dilution part, use the dilution formula M1V1 = M2V2. After dilution the molarity of Na becomes:
M2 = (M1 × V1) / V2 = (0.401 M × 0.0100 L) / 1.000 L = 0.00401 M
- Finally, calculate the concentration in parts per million (ppm) after dilution:
Concentration in ppm = (Moles of Na after dilution / Volume of solution) × Molar mass of Na × 10¶ = (0.00401 M × 1 L) × 22.9898 g/mol × 10¶ ppm/g = 92.25 ppm