A solution is prepared by dissolving 25 grams of sodium sulfate in enough water to give a total volume of 500. mL. The molar mass of sodium sulfate is 142 grams per mole. What is the molarity of the solution?
mols = grams/molar mass.
Solve for mols.
M = mols Na2SO4/L soln
Solve for M.
To find the molarity of a solution, we need to determine the number of moles of the solute (sodium sulfate) and divide it by the volume of the solution in liters.
Given:
Mass of sodium sulfate (solute) = 25 grams
Molar mass of sodium sulfate = 142 grams/mole
Volume of solution = 500 mL = 0.5 L (converted to liters)
First, we need to calculate the number of moles of sodium sulfate using the given mass and molar mass.
Number of moles = Mass / Molar mass
Number of moles = 25 grams / 142 grams/mole
Calculating the moles gives:
Number of moles = 0.1761 moles
Next, we divide the number of moles by the volume of the solution in liters to find the molarity.
Molarity (M) = Number of moles / Volume of solution (in liters)
Molarity = 0.1761 moles / 0.5 L
Calculating the molarity gives:
Molarity = 0.3522 M
Therefore, the molarity of the solution is 0.3522 M.