Assuming 100% dissociation, calculate the freezing point and boiling point of 2.45 m Na2SO4(aq). Constants may be found here sites. google. com/site/chempendix/colligative.
To calculate the freezing point and boiling point of a solution, we need to use the concept of colligative properties. The freezing point depression and boiling point elevation are two colligative properties that depend on the concentration of solute particles in a solution.
Before we begin, it's worth mentioning that in real-world scenarios, not all solute particles fully dissociate. However, in this case, you mentioned assuming 100% dissociation. So, we'll proceed with that assumption.
To calculate the freezing point depression and boiling point elevation, we need to know the van't Hoff factor (i), which represents the number of particles formed by each solute molecule in a solution. For Na2SO4, the van't Hoff factor (i) is 3 because it dissociates into 3 ions (2 Na+ ions and 1 SO4^2- ion) in water.
Now, let's use the formulas for the freezing point depression (ΔTf) and boiling point elevation (ΔTb):
ΔTf = Kf * i * m
ΔTb = Kb * i * m
Where:
Kf is the molal freezing point depression constant for the solvent (water) - found in the link you provided.
Kb is the molal boiling point elevation constant for the solvent (water) - also found in the link you provided.
m is the molality of the solution (moles of solute/kg of solvent).
Given that the concentration of Na2SO4 is 2.45 m, we can assume that 2.45 mol of Na2SO4 is dissolved in 1 kg (1000g) of water.
First, let's calculate the molality (m):
m = moles of solute / kg solvent
In this case, moles of solute = 2.45 mol
kg of solvent = 1 kg
So, m = 2.45 mol / 1 kg = 2.45 m
Now we have the molality (m) value. We can proceed to calculate the freezing point depression and boiling point elevation.
Using the formulas above, we will substitute the values of Kf, Kb, i, and m into the equations to find the values of ΔTf and ΔTb.
After finding ΔTf and ΔTb, we need to add or subtract them from the normal freezing and boiling points of the solvent (water) to get the respective freezing point and boiling point of the solution.
To get the exact values for the freezing and boiling points, you can check the provided link to find the values of Kf and Kb for water and substitute them into the above equations along with the given values.
Just a reminder, make sure to double-check the values from reliable sources, as the link was not accessible in this text-based format.
To calculate the freezing point and boiling point of a solution, we can use the formula for colligative properties:
ΔTf = -Kf × m
ΔTb = Kb × m
Where:
ΔTf = freezing point depression
ΔTb = boiling point elevation
Kf = molal freezing point constant
Kb = molal boiling point constant
m = molality of the solution (moles of solute per kilogram of solvent)
For Na2SO4(aq), we need to retrieve the appropriate values for Kf and Kb. Since we are assuming 100% dissociation, we need to consider that Na2SO4 dissociates into three ions in solution: 2 Na+ ions and 1 SO4²⁻ ion.
Searching for the constants, we find that:
Kf = 1.86 °C/m (for water)
Kb = 0.512 °C/m (for water)
Now we can calculate the freezing point and boiling point:
Step 1: Calculate the molality (m) of the solution.
Since the solution is 2.45 mol Na2SO4 dissolved in 1 kg of water, the molality is:
m = 2.45 mol / 1 kg = 2.45 m
Step 2: Calculate the freezing point depression (ΔTf).
ΔTf = -Kf × m
ΔTf = -1.86 °C/m × 2.45 m
Step 3: Calculate the boiling point elevation (ΔTb).
ΔTb = Kb × m
ΔTb = 0.512 °C/m × 2.45 m
Step 4: Calculate the actual freezing point (Tf).
Tf = Freezing point of the pure solvent - ΔTf
Note: The freezing point of pure water is 0 °C.
Step 5: Calculate the actual boiling point (Tb).
Tb = Boiling point of the pure solvent + ΔTb
Note: The boiling point of pure water is 100 °C.
Plugging in the values, we can calculate the freezing point and boiling point of the Na2SO4 solution.
for f.p.
delta T =i*Kf*m
i = 3 for Na2SO4
m you have
look up Kf. Subtract delta T from 0 C to find new f.p.
for b.p.
delta T = i*Kb*m
look up Kb. You have m and i, add delta T to 100 C to find new boiling point.