Question

A solution of H2SO4(aq) with a molal concentration of 3.97 m has a density of 1.216 g/mL. What is the molar concentration of this solution?

Answer 1

First, we assume 1000 grams of solvent. This means there are 3.97 moles of sulfuric acid. This is equal to 389.06 grams acid. The total mass of the solution is 1389.06 grams. Using density, the number of liters is 1.142 liters. The molarity in this case is equal to 3.475 molar

Answer 2

Answer: Molar Concentration of the solution is 3.475M

Step-by-step explanation:

In order to calculate Molarity from Molality we must clarify its meaning

• Molarity (M) = mol solute / L of solution
• Molality (m) = mol solute / mass (in kg) of the solvent

In this case, we were giving the Molality (m)= 3.97 moles H2SO4/ 1 Kg of H20.

When calculating Molarity (M), we need moles of solute that is already contained in the molality and we need Liters of solution that we can calculate like this:

• Mass of any solution = mass solute + mass solvent
• Mass of any solution = (our case, we use 3.97 moles H2SO4 and using molar mass , we get the mass of the H2SO4) + Mass solvent : We already have it (1Kg H20 =1000g H2O)

Now, let´s calculate the mass solute,:

3.97moles H2SO4 x (98.08g H2SO4 /1mol H2SO4) = 389.4g H2SO4

• Mass of our solution = 389.4g H2SO4 + 1000Kg H20

• Mass of our solution = 1389.4 g Solution

When having the mass of the solution, now we can use the density of the solution to discovery the volumen of the solution.

• 1389.4 g Solution x ( 1mL solution / 1.216g solution)= 1142.6mL solution = 1.1426L solution

Finally, we have the correct values for calculating our molar concentration.

• Molarity (M) = mol solute / L of solution
• Molarity (M) H2SO4= 3.97moles / 1.1426 L solution = 3.475M