If you make a solution by dissolving 25.0g of sodium chloride in 100.0 mL of water. What is the boiling point of the solution?
n=m divided by mr
n=25 divided by mr of nacl 23+35.5
n=c*v
moles NaCl = grams/molar mass
Solve for moles.
molality = moles/kg solvent
Solve for molality
delta T = Kb*m
Solve for delta T. Then add to the normal boiling point.
To determine the boiling point of a solution, you need to know the molality of the solution and the molal boiling-point elevation constant (Kb) for the solvent.
The first step is to calculate the molality (m) of the solution. Molality is defined as the number of moles of solute per kilogram of solvent.
First, convert the mass of sodium chloride (NaCl) to moles. The molar mass of NaCl is approximately 58.44 g/mol.
Number of moles of NaCl = Mass of NaCl / Molar mass of NaCl
Mass of NaCl = 25.0 g
Molar mass of NaCl = 58.44 g/mol
Number of moles of NaCl = 25.0 g / 58.44 g/mol
Next, calculate the mass of water (H2O) in the solution. Remember to convert the volume of water to mass using the density of water, which is 1.00 g/mL.
Mass of water = Volume of water x Density of water
Volume of water = 100.0 mL = 100.0 g
Density of water = 1.00 g/mL
Now, convert the mass of water to kilograms.
Mass of water = 100.0 g = 0.100 kg
With the moles of NaCl (solute) and the mass of water (solvent), you can now calculate the molality of the solution using the formula:
Molality (m) = moles of solute / mass of solvent in kilograms
Now that you have the molality, you can use the formula for boiling point elevation:
ΔTb = Kb * m
Where ΔTb is the change in boiling point, Kb is the molal boiling-point elevation constant for the solvent, and m is the molality of the solution.
For water (H2O), the molal boiling-point elevation constant (Kb) is approximately 0.512 °C/m.
Now, substitute the values into the equation and calculate the boiling point elevation:
ΔTb = 0.512 °C/m * molality of the solution
The boiling point of the solution can be determined by adding the boiling point elevation (ΔTb) to the boiling point of pure water, which is 100 °C.
Boiling point of solution = boiling point of pure water + ΔTb
Calculate ΔTb and add it to 100 °C to find the boiling point of the solution.
Note: This calculation assumes ideal behavior and negligible vapor pressure effects.