What is the molarity of a solution made by dissolving 32.654 g of aluminum sulfate, Al2(SO4)3, in water and diluting with water to 125.0 mL total?
M = mols/L.
mols Al2(SO4)3 = g Al2(SO4)3/molar mass Al2(SO4)3 and L = 0.125.
.241 M
To find the molarity of a solution, we need to calculate the number of moles of solute (Aluminum sulfate Al2(SO4)3) and then divide it by the volume of the solution in liters.
Step 1: Calculate the number of moles of Al2(SO4)3:
- Determine the molar mass of Al2(SO4)3:
Atomic mass of Al = 26.98 g/mol
Atomic mass of S = 32.07 g/mol
Atomic mass of O = 16.00 g/mol
Molar mass of Al2(SO4)3 = (2 x Atomic mass of Al) + (3 x Atomic mass of S) + (12 x Atomic mass of O)
= (2 x 26.98 g/mol) + (3 x 32.07 g/mol) + (12 x 16.00 g/mol)
= 342.15 g/mol
- Convert the mass of Al2(SO4)3 to moles:
Moles of Al2(SO4)3 = mass / molar mass
= 32.654 g / 342.15 g/mol
= 0.0954 mol (rounded to four decimal places)
Step 2: Convert the volume of the solution to liters:
125.0 mL = 125.0 mL x (1 L / 1000 mL)
= 0.125 L
Step 3: Calculate the molarity of the solution:
Molarity (M) = moles of solute / volume of solution (in liters)
= 0.0954 mol / 0.125 L
= 0.7632 M (rounded to four decimal places)
Therefore, the molarity of the solution is 0.7632 M.
To find the molarity of a solution, you need to calculate the number of moles of the solute (aluminum sulfate, Al2(SO4)3) and then divide it by the volume of the solution in liters.
Step 1: Calculate the number of moles of aluminum sulfate (Al2(SO4)3).
- Find the molar mass of aluminum sulfate. The molar mass of aluminum (Al) is 26.98 g/mol, sulfur (S) is 32.07 g/mol, and oxygen (O) is 16.00 g/mol. Since there are 2 aluminum atoms, 3 sulfur atoms, and 12 oxygen atoms in one formula unit of aluminum sulfate, the molar mass is:
(2 * 26.98 g/mol) + (3 * 32.07 g/mol) + (12 * 16.00 g/mol) = 342.15 g/mol
- Use the molar mass to calculate the number of moles of aluminum sulfate:
Moles = Mass / Molar mass
Moles = 32.654 g / 342.15 g/mol
Step 2: Convert the volume of the solution to liters.
- The given volume is 125.0 mL. To convert it to liters, divide by 1000 (since there are 1000 mL in a liter):
Volume = 125.0 mL / 1000 mL/L
Step 3: Calculate the molarity.
- Divide the number of moles by the volume in liters to find the molarity:
Molarity = Moles / Volume
By following these steps, you can calculate the molarity of the solution.