From the following: 1) pure water 2) 0.01 m solution of table sugar (C12H22O11) 3) 0.01 m solution of NaCl 4) 0.01 m solution of CaCl2 Choose the one with the largest van't Hoff factor and hence the lowest freezing point.
See below.
vvs
The van't Hoff factor is a measure of the number of particles formed when a substance dissolves in a solvent. It is given by the equation:
i = (moles of particles in solution)/(moles of formula units dissolved)
For pure water (1), the van't Hoff factor is 1, as water does not dissociate into ions.
For the 0.01 M solution of table sugar (C12H22O11) (2), the van't Hoff factor is 1, as table sugar does not dissociate into ions in water.
For the 0.01 M solution of NaCl (3), the van't Hoff factor is 2, as NaCl dissociates into one Na+ ion and one Cl- ion in water.
For the 0.01 M solution of CaCl2 (4), the van't Hoff factor is 3, as CaCl2 dissociates into one Ca2+ ion and two Cl- ions in water.
Since the 0.01 M solution of CaCl2 (4) has the largest van't Hoff factor of 3, it will have the lowest freezing point among the given options.
To determine the van't Hoff factor and the freezing point, we first need to understand what the van't Hoff factor is and how it affects freezing point.
The van't Hoff factor (i) is the ratio of moles of particles in a solution to the moles of formula units or molecules dissolved. In other words, it measures the number of particles into which a compound dissociates in solution.
The freezing point of a solution is related to the concentration of solute particles in the solution. According to the colligative properties, a solution with a higher number of solute particles will have a lower freezing point compared to a solution with fewer solute particles.
Now, let's consider each solution from the provided options and calculate their van't Hoff factor (i):
1) Pure water (H2O)
Pure water does not dissociate into ions; therefore, it does not increase the number of particles in solution. Hence, the van't Hoff factor for pure water is 1.
2) 0.01 m solution of table sugar (C12H22O11)
Table sugar does not dissociate into ions and remains as a molecule in solution. Hence, the van't Hoff factor for table sugar is also 1.
3) 0.01 m solution of NaCl
NaCl readily dissociates into Na+ and Cl- ions in water. Therefore, it increases the number of particles in solution. Each NaCl formula unit dissociates into two ions when dissolved. Hence, the van't Hoff factor for NaCl is 2.
4) 0.01 m solution of CaCl2
Similarly, CaCl2 dissociates into three ions: one Ca2+ ion and two Cl- ions when dissolved. Therefore, it increases the number of particles in solution. Hence, the van't Hoff factor for CaCl2 is 3.
Comparing the van't Hoff factors for all the solutions, we can conclude that the 0.01 m solution of CaCl2 has the largest van't Hoff factor and, therefore, the lowest freezing point.
To summarize, out of the options provided, the 0.01 m solution of CaCl2 has the largest van't Hoff factor and, therefore, the lowest freezing point.