Question

The weight percent of concentrated HClO4(aq) is 70.5% and its density is 1.67 g/mL. What is the molarity of concentrated HClO4

Answer 1

To find the molarity of concentrated HClO4, calculate the mass of HClO4 in 1 L of solution using the density and weight percent, then convert the mass to moles using the molar mass, and divide by the volume in liters to get molarity, which is 11.72 M.

Step-by-step explanation:

Calculating the Molarity of Concentrated HClO4

First, we must determine the mass of 1 liter (L) of the HClO4 solution. Given the density is 1.67 g/mL, for 1 L (which is 1000 mL), the mass would be 1.67 g/mL × 1000 mL = 1670 g.

With a weight percent of 70.5%, we can calculate the mass of HClO4 in 1 L of solution. This is 70.5% of 1670 g: 0.705 × 1670 g = 1177.35 g.

To find the molarity, we need the molar mass of HClO4, which is 100.46 g/mol. The number of moles in 1177.35 g of HClO4 is calculated by dividing by the molar mass: 1177.35 g / 100.46 g/mol = 11.72 mol.

Finally, since molarity is moles of solute per liter of solution, the molarity is 11.72 mol/L.

Answer 2

[HClO₄] = 11.7M

Step-by-step explanation:

First of all we need to know, that a weight percent represents, the mass of solute in 100 g of solution.

Let's convert the mass to moles → 70.5 g . 1mol/100.45 g = 0.702 moles

Now we can apply the density to calculate the volume.

Density always refers to solution → Solution density = Solution mass / Solution volume

1.67 g/mL = 100 g / Solution volume

Solution volume = 100 g / 1.67 g/mL → 59.8 mL

To determine molarity (mol/L) we must convert the mL to L

59.8 mL . 1L/1000mL = 0.0598 L

Molarity → Moles of solute in 1L of solution → 0.702 mol / 0.0598 L = 11.7M