An aqueous solution contains 2.6 %NaCl by mass. Calculate the molality of the solution.
2.6% NaCl = 2.6 gNaCl in 2.6 g NaCl + 97.4 g H2O.
Convert 2.5 g NaCl to moles.
Convert g H2O to kg H2O.
m = moles/kg solvent. You should get about 0.5 m. Post your work if you get stuck.
To calculate the molality of the solution, we need to know the mass of the solute (NaCl) and the mass of the solvent (water).
In this case, the solution contains 2.6% NaCl by mass, which means that for every 100 grams of the solution, there are 2.6 grams of NaCl.
Let's assume we have 100 grams of the solution. Therefore, there will be 2.6 grams of NaCl.
Now we need to calculate the mass of water in the solution. Since the total mass of the solution is 100 grams, and we have 2.6 grams of NaCl, the remaining mass must be water.
The mass of water = Total mass of solution - Mass of NaCl
Mass of water = 100 grams - 2.6 grams
Mass of water = 97.4 grams
Next, we need to convert the mass of NaCl and the mass of water into moles.
First, let's calculate the moles of NaCl.
Moles of NaCl = Mass of NaCl / Molar mass of NaCl
The molar mass of NaCl is 58.44 g/mol (22.99 g/mol for sodium + 35.45 g/mol for chlorine).
Moles of NaCl = 2.6 grams / 58.44 g/mol
Moles of NaCl ≈ 0.0445 mol
Now, let's calculate the molality of the solution.
Molality (m) = Moles of solute / Mass of solvent (in kg)
But we have the mass of the solvent in grams, so we need to convert it to kilograms.
Mass of water in kg = Mass of water / 1000
Mass of water in kg = 97.4 grams / 1000
Mass of water in kg = 0.0974 kg
Molality (m) = 0.0445 mol / 0.0974 kg
Molality (m) ≈ 0.457 mol/kg
Therefore, the molality of the solution is approximately 0.457 mol/kg.