A solution of HCI has a density of 1.18 g/ml and is 36% (m/m). what is the molarity and molality of this solution?
Assume 100g solution. Then the solute is 36 grams. Figure the moles for that.
Then, you know density, so you can compute volume (100g/density)
Molarity= moles solute/liters solution
molality= moles solute/kg solvent
To find the molarity and molality of the solution, we will first calculate the number of moles of solute (HCl) present in the solution.
Given that the solution is 36% (m/m), this means that there are 36 grams of HCl in every 100 grams of the solution. Therefore, assuming we have 100 grams of the solution, the mass of HCl in the solution would be 36 grams.
Next, we will calculate the moles of HCl using the molar mass of HCl, which is 36.46 g/mol (hydrogen has a molar mass of 1.01 g/mol and chlorine has a molar mass of 35.45 g/mol).
Moles of HCl = mass of HCl / molar mass of HCl
= 36 g / 36.46 g/mol
≈ 0.9867 mol
Now, to determine the molarity, we will need to calculate the volume of the solution using the density given.
Density = mass / volume
Rearranging the equation, we get:
Volume = mass / density
= 100 g / 1.18 g/ml
≈ 84.746 ml
Since molarity is defined as moles of solute divided by the volume of the solution in liters, we can now calculate the molarity.
Molarity = moles of solute / volume of solution (in liters)
= 0.9867 mol / (84.746 ml / 1000 ml/L)
≈ 11.6197 M (rounded to four decimal places)
Finally, we can calculate the molality of the solution using the mass of solvent (water in this case) and the moles of solute.
Since we assumed a 100g solution, the mass of the solvent would be:
Mass of solvent = mass of solution - mass of solute
= 100 g - 36 g
= 64 g
Molality = moles of solute / mass of solvent (in kg)
= 0.9867 mol / (64 g / 1000 g/kg)
≈ 15.4164 m (rounded to four decimal places)
Therefore, the molarity of the solution is approximately 11.6197 M and the molality is approximately 15.4164 m.