The density of 3M solution of NaCl is 1.25 g/mL. Calculate the molality of the solution.
see below
To calculate the molality of a solution, we need to know the mass of the solute (in this case, NaCl) and the mass of the solvent (typically water), as well as the molar mass of the solute.
However, in this question, we are given the density of the solution, not the mass of the solute. So, in order to calculate the molality, we need to first find the mass of the solute.
Given:
Density of the solution = 1.25 g/mL
The density of the solution can be used to find the mass of 1 liter (1000 mL) of the solution, since the density is given in grams per milliliter. Hence, the mass of the solution is:
Mass of 1 liter of the solution = density × volume
= 1.25 g/mL × 1000 mL
= 1250 g
Now, let's assume that the mass of the solvent (water) is negligible compared to the mass of the solution. Therefore, we can consider the mass of 1 liter of the solution as the mass of the solvent.
To calculate the molality, we need to know the molar mass of sodium chloride (NaCl), which is approximately 58.44 g/mol.
Molality (m) = moles of solute / mass of solvent (in kg)
To find the molality, we need to calculate the moles of NaCl present in the solution. To do this, we'll use the formula:
Moles = mass / molar mass
Mo