A student dissolves 2.57 grams of iodine [molar mass= 257]in 10.0 grams of carbon tetrachloride [kb = 5.03C/m]. The normal boiling point of carbon tetrachloride is approximately 77degreesC. What is the approximate boiling point of the solution above?
molality= 2.57/257 )/.010
bpnew=77+kb*m
To determine the approximate boiling point of the solution, we need to use the concept of boiling point elevation. The formula we will use is:
ΔTb = Kb * m
where ΔTb represents the boiling point elevation, Kb is the molal boiling point elevation constant of the solvent, and m is the molality of the solution.
First, we need to calculate the molality (m) of the solution. Molality is defined as the number of moles of solute per kilogram of solvent. To calculate molality, we need to determine the number of moles of iodine (the solute) and the mass of the carbon tetrachloride (the solvent).
The number of moles of iodine can be calculated using its given mass and molar mass:
moles of iodine = mass of iodine / molar mass of iodine
= 2.57 g / 257 g/mol
≈ 0.01 mol
Next, we calculate the mass of carbon tetrachloride:
mass of carbon tetrachloride = 10.0 g
Now, we can calculate the molality (m):
m = moles of iodine / mass of carbon tetrachloride (in kg)
= 0.01 mol / 0.010 kg
= 1 mol/kg
Now, we have the molality value. We can use the given molal boiling point elevation constant (Kb = 5.03°C/m) and the molality (m) to calculate the boiling point elevation (ΔTb):
ΔTb = Kb * m
= 5.03°C/m * 1 mol/kg
= 5.03°C
Finally, we can determine the approximate boiling point of the solution by adding the boiling point elevation to the normal boiling point of the solvent:
Boiling point of the solution = Normal boiling point of the solvent + ΔTb
= 77°C + 5.03°C
≈ 82.03°C
Therefore, the approximate boiling point of the solution is approximately 82.03°C.