Calculate the boiling point of a 4.0 m solution of KI in water. Remember that KI is an electrolyte. The normal boiling point of pure water is 100.0ºC. K_b (water)= 0.52ºC/m. A)101.0 ºC B)104.2ºC C)96.0ºC D)102.1ºC E)4.16ºC

Question

Quizplus · Accepted Answer

The boiling point elevation can be calculated using the formula ∆Tb = Kb x m, where ∆Tb is the boiling point elevation, Kb is the molal boiling point constant (0.52ºC/m for water), and m is the molality (moles of solute per kilogram of solvent).

First, we need to calculate the molality of the solution. To do this, we need to know the molar mass of KI, which is 166 g/mol. We also need to know how many moles of KI are in the solution. Assuming we have 1 kg of water (which is equivalent to 1 L, since the density of water is 1 g/mL), we can calculate the mass of KI needed to make a 4.0 m solution:

4.0 mol KI / kg water x 166 g KI/mol = 664 g KI

Therefore, we need 664 g of KI to make a 4.0 m solution in 1 kg of water.

Now we can calculate the molality:

molality = moles of solute / mass of solvent in kg
molality = 4.0 mol / 1 kg = 4.0 m

Finally, we can calculate the boiling point elevation:

∆Tb = Kb x m = 0.52ºC/m x 4.0 m = 2.08ºC

The boiling point of the solution is then:

boiling point = normal boiling point + ∆Tb
boiling point = 100.0ºC + 2.08ºC = 102.1ºC

Therefore, the best choice is B.

Calculate the Boiling Point of a 4