Question

Urea, (NH₂)₂CO, is a product of metabolism of proteins. An aqueous solution is 34% urea by mass and has a density of 1.054 g/ml. Calculate the molarity of urea in this solution.

Answer 1

To calculate the molarity of urea, the percentage by mass, the density of the solution, the molecular weight of urea, and the volume of the solution in liters are used in a series of calculations that convert mass in grams to moles, and then divide by liters to reach the concentration in moles per liter.

Step-by-step explanation:

To calculate the molarity of urea in a given aqueous solution, apply the steps involving percentage by mass, density of the solution, molecular weight of urea, and the definition of molarity. First, determine the mass of urea per liter of solution using the given percentage by mass and the density. Then, convert this mass to moles using the molar mass of urea. Finally, divide the number of moles by the volume of the solution in liters to obtain the molarity.

Here is how you can perform the calculations:

• Determine the mass of urea per 100 g of solution (34% of 100 g is 34 g).
• Calculate the mass of urea in 1 liter of solution by multiplying its density (1.054 g/ml) by 1000 ml.
• Convert this mass to moles using urea's molar mass (60.06 g/mol).
• Finally, calculate the molarity by dividing the number of moles by the volume of the solution in liters.

Through these steps, you can derive the molarity of the urea solution, which represents its concentration in terms of moles per liter, a fundamental concept in chemistry.