Calculating Molality of a Sulfuric Acid Solution

In summary, to find the molality of a 77.0% solution of sulfuric acid with a density of 1.303 g/mL, you need to first convert the percentage concentration to a fraction, then use the density to calculate the amount of solvent (in kg), and finally use the molecular weight of H2SO4 to convert the amount of solute (in g) to moles. The result should be in moles of H2SO4 per kilogram of solvent. If you need to also find the molarity, the density conversion factor will be needed.
  • #1
Ki-nana18
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Homework Statement


You are given a 77.0% solution of sulfuric acid, H2SO4. What is the molality of this solution? The density of the H2SO4 solution is 1.303 g/mL.


Homework Equations





The Attempt at a Solution


I know I divide 77.0 by 100, and then I have no idea from there.
 
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  • #2
Molality means the number of moles of solute in one kilogram of SOLVENT.

Express your percentage concentration as a fraction or ratio, using a numerator and a denominator. You are given the density of solution, and you may need the the molecular weight of H2SO4. Your targe result is to be in moles of H2SO4 per kilogram of water. You should obviously understand that 77.0% means [tex]\frac{77}{100}[/tex].
 
  • #3
Molality means moles solute over kg solvent but it did not say the solution was aqueous, so do not assume the solvent is water. Assume 77g in 100g solution. 100g-77g=23g solvent. Convert to kg solvent. Last step would be to convert the 77g sulfuric acid to moles using the molecular weight from the periodic table. If you need to convert to Molarity also, that's where the density conversion factor will be needed.
 

FAQ: Calculating Molality of a Sulfuric Acid Solution

1. What is concentration of a solution?

Concentration of a solution refers to the amount of solute (substance being dissolved) per unit volume of the solvent (liquid in which the solute is dissolved). It is usually expressed in units of moles per liter (mol/L) or grams per liter (g/L).

2. How is concentration of a solution calculated?

Concentration of a solution is calculated by dividing the amount of solute (in moles or grams) by the volume of the solution (in liters). This gives the concentration in units of mol/L or g/L.

3. Why is concentration of a solution important?

Concentration of a solution is important because it affects the properties and behavior of the solution. It determines the strength of a solution, its ability to dissolve other substances, and can also impact chemical reactions and reactions rates.

4. How does concentration of a solution affect osmosis?

Concentration of a solution plays a crucial role in osmosis, which is the movement of water molecules across a semi-permeable membrane from an area of lower solute concentration to an area of higher solute concentration. The higher the concentration of solute, the lower the concentration of water molecules, and the more water molecules will move across the membrane to equalize the concentration on both sides.

5. How can concentration of a solution be changed?

Concentration of a solution can be changed by adding more solute to the solution (increasing concentration) or by adding more solvent (decreasing concentration). It can also be changed by changing the volume of the solution, for example by diluting it with more solvent.

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