If 0.500 mol of each of the following solutes is dissolved in 2.0 L of water, which will cause the greatest increase in the boiling point of the solution?
A. KI
B. CO2
C. Na2SO4
D. NaCl
delta T = i*Kb*m
Look at this logically. m = mols/kg solvent; therefore, m is constant for all of these. Kb, the boiling point constant is a constant for all of these. Therefore, the ONLY variable is i.
i = 2 for A
i = 1 for B
i = 3 for C.
i = 2 for D.
i is the van't Hoff factor.
So the solute with the largest delta T, when added to the normal boiling point of water will have the highest boiling point.
To determine which solute will cause the greatest increase in the boiling point of the solution, we need to compare the van't Hoff factor (i) for each solute. The van't Hoff factor is a measure of the number of particles the solute dissociates into when it dissolves in water.
The van't Hoff factor (i) for each solute can be determined based on their chemical formulas. Here are the formulas of the solutes mentioned:
A. KI (potassium iodide) - KI dissociates into K+ and I- ions in water, so the van't Hoff factor (i) for KI is 2.
B. CO2 (carbon dioxide) - CO2 molecules do not dissociate into ions in water, so the van't Hoff factor (i) for CO2 is 1.
C. Na2SO4 (sodium sulfate) - Na2SO4 dissociates into 2 Na+ ions and 1 SO4^2- ion in water, so the van't Hoff factor (i) for Na2SO4 is 3.
D. NaCl (sodium chloride) - NaCl dissociates into 1 Na+ ion and 1 Cl- ion in water, so the van't Hoff factor (i) for NaCl is 2.
Now we can compare the van't Hoff factors to determine which solute will cause the greatest increase in boiling point. The higher the van't Hoff factor, the greater the increase in boiling point.
Comparing the van't Hoff factors:
A. KI (i = 2)
B. CO2 (i = 1)
C. Na2SO4 (i = 3)
D. NaCl (i = 2)
From the comparison, we can see that Na2SO4 has the highest van't Hoff factor (i = 3), indicating that it will cause the greatest increase in the boiling point of the solution when 0.500 mol of each solute is dissolved in 2.0 L of water.
Therefore, the answer is C. Na2SO4.