Question

an aqueous Na₂S₄ solution is made using 73.5 g of Na₂S₄ diluted to a total solution volume of 0.200 l. calculate the molarity, molality, and mass percent of the solution. (assume a density of 1.05 g/ml for the solution.)

Answer 1

The molarity of the Na₂S₄ solution is 8.0 M, the molality is 7.62 m, and the mass percent is 35,000%.

Step-by-step explanation:

To calculate the molarity of the Na₂S₄ solution, first we need to find the number of moles of Na₂S₄.

1. 
   
2. Calculate the molar mass of Na₂S₄:
   2 x (22.99 g/mol) + 4 x (32.07 g/mol) = 46.0 g/mol
3. 
   
4. Convert the mass of Na₂S₄ to moles:
   73.5 g / 46.0 g/mol = 1.60 mol
5. 
   
6. Calculate the volume of the solution in liters:
   0.200 L
7. 
   
8. Calculate the molarity:
   Molarity (M) = moles / volume
   M = 1.60 mol / 0.200 L = 8.0 M

To calculate the molality of the Na₂S₄ solution, we need to find the mass of solvent (water in this case) and the number of moles of Na₂S₄.

1. 
   
2. Calculate the mass of water:
   density = 1.05 g/mL
   volume = 0.200 L
   mass = density x volume
   mass = 1.05 g/mL x 0.200 L = 0.210 g
3. 
   
4. Calculate the molality:
   Molality (m) = moles of solute / mass of solvent
   m = 1.60 mol / 0.210 kg = 7.62 m

To calculate the mass percent of the Na₂S₄ solution, we need to find the mass of Na₂S₄ and the total mass of the solution.

1. 
   
2. Calculate the total mass of the solution:
   density = 1.05 g/mL
   volume = 0.200 L
   mass = density x volume
   mass = 1.05 g/mL x 0.200 L = 0.210 g
3. 
   
4. Calculate the mass percent of Na₂S₄:
   Mass percent = (mass of Na₂S₄ / total mass of solution) x 100%
   Mass percent = (73.5 g / 0.210 g) x 100%
   Mass percent = 35,000%
5.