Question

An aqueous solution of HCl is 38% by mass and its density is L1.19 gm'm. Calculate the molality and molarity of solution (HCL-36.5)​

Answer 1

Question:

An aqueous solution of HCl is 38% by mass and its density is 1.19 gm/ml. Calculate the molality and molarity of the solution.

Answer:

Molality = 16.77 m

Molarity = 12.38 M

Explanation:

Given:

• Weight of HCl = 38 g
• Density = 1.19 gm/ml
• Molar mass of solute = 36.5 g

To Find:

• Molality
• Molarity

Concept:

First find the number of moles of solute and substituting it in the formula, we get the value of molality. Next finding the volume of the solution and then substituting it in the formula we get the value of molarity.

Solution:

First we have to find the number of moles of solute.

Number of moles of solute is given by,

Number of moles of solute = Given mass/Molar mass

Substitute the data,

Number of moles of solute = 38/36.5

Number of moles of solute = 1.04 moles

Now mass of solvent = 100 - 38

Mass of solvent = 62 g = 0.062 kg

Now,

Molality is given by the equation,

Molality = number of moles of solute/Mass of solvent in kg

Substitute the data,

Molality = 1.04/0.062

Molality = 16.77 m

$\boxed{\bold{Molality=16.77\:m}}$

Now we have to find the volume of the solution.

We know that,

Volume = Mass/Density

Volume = 100/1.19

Volume = 84 ml = 0.084 L

Now molarity is given by,

Molarity = number of moles of solute/Volume of solution in L

Substitute the data,

Molarity = 1.04/0.084

Molarity = 12.38 M

$\boxed{\bold{Molarity=12.38\:M}}$

Answer 2

__________________________________________________

Question:

An aqueous solution of HCl is 38% by mass and its density is 1.19 gm/ml. Calculate the molality and molarity of the solution.

Answer:

Molality = 16.77 m

Molarity = 12.38 M

Explanation:

Given:

Weight of HCl = 38 g

Density = 1.19 gm/ml

Molar mass of solute = 36.5 g

To Find:

Molality

Molarity

Concept:

First find the number of moles of solute and substituting it in the formula, we get the value of molality. Next finding the volume of the solution and then substituting it in the formula we get the value of molarity.

Solution:

First we have to find the number of moles of solute.

Number of moles of solute is given by,

Number of moles of solute = Given mass/Molar mass

Substitute the data,

Number of moles of solute = 38/36.5

Number of moles of solute = 1.04 moles

Now mass of solvent = 100 - 38

Mass of solvent = 62 g = 0.062 kg

Now,

Molality is given by the equation,

Molality = number of moles of solute/Mass of solvent in kg

Substitute the data,

Molality = 1.04/0.062

Molality = 16.77 m

Molality=16.77

Molality=16.77m

Now we have to find the volume of the solution.

We know that,

Volume = Mass/Density

Volume = 100/1.19

Volume = 84 ml = 0.084 L

Now molarity is given by,

Molarity = number of moles of solute/Volume of solution in L

Substitute the data,

Molarity = 1.04/0.084

Molarity = 12.38 M

\boxed{\bold{Molarity=12.38\:M}}

Molarity=12.38M