A sample of 12 M12 M concentrated hydrochloric acid has a density 1.2 gL–11.2 gL–1. Calculate the molality. (Write only numerical value and round off to two decimal digits).

To calculate the molality, we need to know the formula for molality which is moles of solute per kilogram of solvent.

Given:

• Molarity (M) = 12 M
• Density of HCl = 1.2 g/mL

First, we need to convert the density from g/mL to g/L by multiplying by 1000 (since 1 L = 1000 mL). So, the density is 1200 g/L.

Since molarity is defined as moles of solute per liter of solution, we can find the number of moles in 1 L of the solution by multiplying the molarity by the volume in liters. So, the number of moles of HCl in 1 L of the solution is 12 moles.

The mass of the solution is the density times the volume, so the mass of 1 L of the solution is 1200 g.

However, molality is defined in terms of kilograms of solvent, not grams of solution. So, we need to convert the mass of the solution to kilograms by dividing by 1000. So, the mass of the solution is 1.2 kg.

Finally, we can calculate the molality by dividing the number of moles of solute by the mass of the solvent in kilograms.

So, the molality is 12 moles / 1.2 kg = 10 mol/kg.

Therefore, the molality of the solution is 10.