Question

The mass of urea required in making 5 kg of 5 molal aqueous solution is

Answer 1

Answer :

Moles of urea given = 5 mole

Mass of urea = 60 g mol^-1

Now, 5 moles of urea = 5×60 = 300 g

So, Mass of the solution = 1000+300 = 1300 g = 1.3 kg

Hence, 5 kg of solution contains = (300/1.3)×5 = 230.7×5 = 1,153.8 kg

Extra Information :

The different ways in which we can express concentration of a solution are :

• Mass percentage : The mass percent of a component is the mass of the component in the solution by total mass of solution multiplied by 100.
• Volume percentage : The volume percentage is defined as the volume of the component by total volume of the solution into 100.
• Mass by volume percentage : It is the mass of solute dissolved in 100 ml of the solution.
• Parts per million : It is defined as the number of parts of the component by total number of parts of all components of the solution into 10⁶.
• Mole fraction : The mole fraction of a component is defined as number of moles of the component by total number of moles of all the components.
• Molarity : Molarity (M) is defined as the number of moles of solute dissolved in one litre of the solution.
• Molality : Molality (m) is defined as the number of moles of the solute per kilogram of the solvent.

Answer 2

Explanation:

Answer ✍️

_____________

Moles of urea given = 5 mole

Mass of urea = 60 g mol^-1

Now, 5 moles of urea

• = 5×60 = 300 g

So, Mass of the solution

• = 1000+300 = 1300 g = 1.3 kg

Hence, 5 kg of solution contains

• = (300/1.3)×5 = 230.7×5 = 1,153.8 kg

Extra Information :

The different ways in which we can express concentration of a solution are :

Mass percentage : The mass percent of a component is the mass of the component in the solution by total mass of solution multiplied by 100.

• Volume percentage : The volume percentage is defined as the volume of the component by total volume of the solution into 100.
• Mass by volume percentage : It is the mass of solute dissolved in 100 ml of the solution.
• Parts per million : It is defined as the number of parts of the component by total number of parts of all components of the solution into 10⁶.
• Mole fraction : The mole fraction of a component is defined as number of moles of the component by total number of moles of all the components.
• Molarity : Molarity (M) is defined as the number of moles of solute dissolved in one litre of the solution.
• Molality : Molality (m) is defined as the number of moles of the solute per kilogram of the solvent.

hope this helps you