A solution is 3.00M NaCl. The solution density is 1.05 g/mL. Calculate the molality?
3 M means 3 mols/L of solution which is 3*molar ,mass NaCl = approx 175 g NaCl/L solution
mass of the 1L = 1000 mL x 1.05 g/mL = 1050g solution - 175 = appox 875 g H2O or 0.875 kg.
m = mols/kg solvent = about 175/0.875 = ?
You need to work the problem with more accuracy than I've done.
To calculate the molality of a solution, we need to know the mass of the solute (in moles) and the mass of the solvent (in kilograms).
First, let's calculate the mass of the solute (NaCl):
Given:
Solution density = 1.05 g/mL
Volume of the solution is not given, so assume 1 L for convenience
Mass of the solution = Solution density * Volume of the solution
Mass of the solution = 1.05 g/mL * 1000 mL (since 1 L = 1000 mL)
Mass of the solution = 1050 g
To calculate the mass of NaCl, we need to determine the concentration of NaCl in the solution. The concentration is given as 3.00 M, which means 3.00 moles of NaCl per liter of solution.
So, the mass of NaCl = 3.00 moles * molar mass of NaCl
The molar mass of NaCl (sodium chloride) is 58.44 g/mol.
Mass of NaCl = 3.00 moles * 58.44 g/mol
Mass of NaCl = 175.32 g
Now, we have the mass of the solute (NaCl = 175.32 g) and the mass of the solvent (1050 g).
Next, let's calculate the molality:
Molality (m) = Moles of solute / Mass of solvent (in kg)
First, convert the mass of the solvent from grams to kilograms:
Mass of solvent (in kg) = 1050 g / 1000 g/kg
Mass of solvent (in kg) = 1.05 kg
Now calculate the molality:
Molality (m) = 175.32 g / 1.05 kg
Molality (m) = 166.972 mol/kg (rounding to three significant figures)
Therefore, the molality of the 3.00 M NaCl solution is approximately 167 mol/kg.
To calculate the molality (m) of a solution, we need to know the mass of the solute (in this case, NaCl) and the mass of the solvent (in this case, water), as well as the molar mass of the solute.
First, let's calculate the mass of NaCl in the solution. We have 3.00M NaCl, which means there are 3.00 moles of NaCl per liter of solution. Since the density of the solution is given as 1.05 g/mL, we can calculate the mass of the solution using the volume.
The mass of 1 mL of the solution can be calculated by multiplying the density by the volume:
1 mL x 1.05 g/mL = 1.05 g
Since 1 liter is the same as 1000 mL, the mass of 1000 mL (1 liter) of the solution is:
1000 mL x 1.05 g/mL = 1050 g
Now, to calculate the mass of NaCl in the solution, we multiply the volume of the solution (in liters) by the molarity of NaCl:
Mass of NaCl = 3.00 M x 1 liter = 3.00 moles
Next, we need the molar mass of NaCl. Na (sodium) has a molar mass of 22.99 g/mol, and Cl (chlorine) has a molar mass of 35.45 g/mol, so the molar mass of NaCl is:
22.99 g/mol + 35.45 g/mol = 58.44 g/mol
Now we can calculate the molality (m) using the formula:
m = (moles of solute) / (mass of solvent in kg)
Since 1 liter of water has a mass of 1000 g, which is 1 kg, our formula becomes:
m = (3.00 moles) / (1050 g / 1000)
m = (3.00 moles) / (1.05 kg)
m = 2.86 mol/kg
Therefore, the molality of the 3.00M NaCl solution is 2.86 mol/kg.