The boiling point of water at 735mmHg is 99.073C. What mass of NaCl should be added to 3.11kg water to increase the boiling point to 100.000C. Kb for water = 0.510K kg mol-1.
delta T = Kb*molality
Solve for molality.
m = moles/kg solvent.
Solve for moles.
moles = grams/molar mass
Solve for grams.
g BaCl2 = 1.38moles BaCl2 x molar mass BaCl2 (which is 208.23)
=287.3574g
To determine the mass of NaCl that needs to be added to increase the boiling point of water, we can use the equation:
ΔT = Kb * m * i
where:
ΔT is the change in boiling point
Kb is the boiling point elevation constant for water
m is the molality of the solution
i is the van't Hoff factor for NaCl (which is 2)
Step 1: Calculate the change in boiling point (ΔT)
Given:
Boiling point of water at 735 mmHg = 99.073°C
New boiling point = 100.000°C
ΔT = New boiling point - Boiling point at 735 mmHg
= 100.000°C - 99.073°C
= 0.927°C
Step 2: Calculate the molality (m) of the NaCl solution
Given:
Mass of water = 3.11 kg
Moles of water = Mass of water / Molar mass of water
= 3.11 kg / 18.015 g/mol
= 172.5 mol
Molality (m) = Moles of solute (NaCl) / Mass of solvent (water in kg)
= Moles of NaCl / Mass of water
Since we don't know the moles of NaCl yet, we need to calculate it.
Step 3: Calculate the moles of NaCl required
Using the equation:
ΔT = Kb * m * i
0.927°C = 0.510 K kg mol-1 * m * 2
Simplifying the equation:
m = (0.927°C) / (0.510 K kg mol-1 * 2)
m = 0.909 mol/kg
Since m = Moles of NaCl / Mass of water, we can rearrange the equation to find the moles of NaCl:
Moles of NaCl = m * Mass of water
= 0.909 mol/kg * 3.11 kg
= 2.829 mol
Step 4: Calculate the mass of NaCl required
Now, we can calculate the mass of NaCl using its molar mass, which is 58.44 g/mol.
Mass of NaCl = Moles of NaCl * Molar mass of NaCl
= 2.829 mol * 58.44 g/mol
= 165.4 g
Therefore, approximately 165.4 grams of NaCl should be added to 3.11 kg of water to increase the boiling point to 100.000°C.