Calculate the freezing point and boiling point of a solution that contains 57.0 g NaCl and 53.4 g KBr dissolved in 750.3 mL H2O

moles NaCl = grams/molar mass = ??

moles KBr = grams/molar mass = ??
Add moles NaCl + moles KBr.
molality = total moles/kg solvent
delta T = i*Kf*molality
i = 2

delta T = i*Kb*molality
i = 2

thanks

To calculate the freezing point and boiling point of a solution, you need to use the concept of colligative properties and the molality of the solute.

First, let's calculate the molality (m) of each solute. Molality is defined as the number of moles of solute per kilogram of solvent.

1. Calculate the number of moles of NaCl:
- Convert the mass of NaCl to moles by dividing the mass by the molar mass of NaCl (22.99 g/mol for Na, and 35.45 g/mol for Cl).
- Moles of NaCl = mass of NaCl / molar mass of NaCl

2. Calculate the number of moles of KBr in a similar way:
- Convert the mass of KBr to moles by dividing the mass by the molar mass of KBr (39.10 g/mol for K, and 79.90 g/mol for Br).
- Moles of KBr = mass of KBr / molar mass of KBr

3. Calculate the mass of water (solvent) in the solution:
- Convert the volume of water to grams by multiplying the volume by the density of water (1 mL = 1 g).
- Mass of water = volume of water * density of water

4. Calculate the total mass of the solution:
- Total mass = mass of NaCl + mass of KBr + mass of water

5. Calculate the molality of NaCl:
- Molality (m) of NaCl = moles of NaCl / mass of water (in kg)

6. Calculate the molality of KBr:
- Molality (m) of KBr = moles of KBr / mass of water (in kg)

Now, let's use the molality values to calculate the freezing point and boiling point changes of the solution.

Freezing Point Depression:
The freezing point depression is given by the equation:

ΔTf = Kf * m

where:
ΔTf is the freezing point depression,
Kf is the cryoscopic constant for the solvent (water),
and m is the molality of the solute.

7. Look up the cryoscopic constant (Kf) for water. For water, Kf = 1.86 °C/m.

8. Calculate the freezing point depression for NaCl and KBr using their respective molality values:
- ΔTf of NaCl = Kf * m of NaCl
- ΔTf of KBr = Kf * m of KBr

9. Calculate the freezing point of the solution:
- Freezing point = freezing point depression + freezing point of pure solvent

Boiling Point Elevation:
The boiling point elevation is given by the equation:

ΔTb = Kb * m

where:
ΔTb is the boiling point elevation,
Kb is the ebullioscopic constant for the solvent (water),
and m is the molality of the solute.

10. Look up the ebullioscopic constant (Kb) for water. For water, Kb = 0.512 °C/m.

11. Calculate the boiling point elevation for NaCl and KBr using their respective molality values:
- ΔTb of NaCl = Kb * m of NaCl
- ΔTb of KBr = Kb * m of KBr

12. Calculate the boiling point of the solution:
- Boiling point = boiling point elevation + boiling point of pure solvent

By following these steps, you can calculate the freezing point and boiling point of the given solution.