Dissolving 120 g of urea (mol. wt. 60) in 1000 g of water gave a solution of density 1.15 g/mL The molarity of the solution is
x= percentage by weight
To find the molarity of the urea solution, we need to understand that molarity (M) is defined as the number of moles of solute per liter of solution. The formula is:
where n is the number of moles of solute and V is the volume of the solution in liters.
Step 1: Calculate the number of moles of urea (n)
Given mass of urea = 120 g, Molar mass of urea = 60 g/mol
Step 2: Calculate the total mass of the solution
Mass of solute (urea) = 120 g, Mass of solvent (water) = 1000 g
Total mass = 120 g + 1000 g = 1120 g
Step 3: Calculate the volume of the solution (V) using density
Density = 1.15 g/mL, which means 1.15 g of solution occupies 1 mL volume.
So, volume of solution in mL = Total mass / Density = 1120 g / 1.15 g/mL
Convert to liters: V(L) = 973.913 / 1000 = 0.973913 L
Step 4: Calculate molarity
So, the molarity of the solution is approximately 2.05 M.
Molarity (M): It is a concentration term defined as moles of solute per liter of solution. Formula:
Density: Density of a solution is mass per unit volume. It is used to find the volume when mass is known. Formula:
Mole Concept: Number of moles is calculated as mass divided by molar mass. Formula: