Thread: Using Equations to Solve for molarity, volume of solution, and moles of a solute

I am using the formulas for molarity: M = Mol/L, L = mol/M, & Mol = M x L to solve the following two equations.(I solved them both, i just need help figuring out what errors i made in my calculations, i've posted the answers as well)

1) For an aqueous solution of Sucrose (C12H22O11), determine the molarity of 5.00 L of a solution that contain 235 g of sucrose, the volume of this solution that would contain 1.26 mole of sucros, and the number of moles of sucrose in 1.89 L of this solution.

molar mass: 342.30 g

moles of sucrose: 235g/342.30 g = 1.46 mol

molarity: 1.46 mol/5.00 L = 3.42 Should be: 0.137 M

b) volume: 1.26 mole/ 3.42 mole = 2.71 Should be: 9.18 L

c) 2.71 m x 1.89 L = 5.12 moles of sucrose Should be: 0.259 mol


2) For an aqueous solution of sodium chloride (NaCl), determine the molarity of 3.75 L of a solution that contains 155 g of sodium chloride, the volume of this solution that would contain 4.58 moles of sodium chloride, and the number of moles of sodium chloride in the 22.75L of this solution.

Sodium Chloride: 58.44 g molar mass

moles of NaCl: 58.44/155 = 2.65 moles

molarity: 2.65 moles/3.75 = 9.42 Should be: .707 M

b) volume: 1.42 m/4.58 moles: 3.23 Should be: 6.48 L

c) 22.75L x 3.23 = 73.48 moles of NaCl Should be: 16.1 mol

You are dividing incorrectly in your second line.

Oh okay i see now. Thank you.