Understanding Molarity Calculation for H2SO4 Solutions

Molarity is a fundamental concept in chemistry that describes the concentration of a solution in moles per liter. This article will guide you through the process of calculating the molarity of a 20% H2SO4 solution, taking into account different given densities and concentrations. Let's break down the steps and formulas to ensure accurate calculations.

Given Information and Context

Initially, we are presented with different scenarios involving the density and concentration of a 20% H2SO4 solution. The density of the solution can significantly affect the calculation, so we need to use the correct values to get the accurate molarity. Here, we will explore two scenarios with different densities:

Scenario 1: Density of 1.0661 g/mL

The density given is 1.0661 g/mL, and the solution is 20% by mass (m/m).

First, calculate the mass of the solution using the volume and density:

mass_solution  0.2 (m) x 1.0661 (g/mL) x 1000 (mL)  213.22 (g)

Next, calculate the mass of H2SO4 in the solution:

mass_H2SO4  0.2 (m) x 213.22 (g)  42.644 (g)

Use the molar mass of H2SO4 (98 g/mol) to convert the mass to moles:

moles_H2SO4  42.644 (g) / 98 (g/mol)  0.435 (mol)

Finally, calculate the molarity by dividing the moles of H2SO4 by the volume of the solution (assuming 1 L for 1000 mL of solution):

molarity  0.435 (mol) / 1 (L)  0.435 M

Scenario 2: Density of 1.14 g/mL

The density given is 1.14 g/mL, and the solution is 20% by mass (m/m).

First, calculate the mass of the solution using the volume and density:

mass_solution  0.2 (m) x 1.14 (g/mL) x 1000 (mL)  228 (g)

Next, calculate the mass of H2SO4 in the solution:

mass_H2SO4  0.2 (m) x 228 (g)  45.6 (g)

Use the molar mass of H2SO4 (98 g/mol) to convert the mass to moles:

moles_H2SO4  45.6 (g) / 98 (g/mol)  0.465 (mol)

Finally, calculate the molarity by dividing the moles of H2SO4 by the volume of the solution (assuming 1 L for 1000 mL of solution):

molarity  0.465 (mol) / 1 (L)  0.465 M

Conclusion

While it is true that different given densities can affect the calculations, the 20% H2SO4 solution with a density of 1.0661 g/mL and 1.14 g/mL were calculated using the correct steps. It's important to use the correct density as it directly impacts the mass of the solute and the subsequent molarity of the solution.

Related Keywords: molarity, H2SO4, density, solution concentration