Which of the two aqueous solutions has a higher boiling point 0.35mCaCl2 or 0.9m urea?
delta T = i*Kb*m
For CaCl2, i = 3 and m = 0.35
For urea, i = 1 and m = 0.9
Kb is the same for both.
To determine which of the two aqueous solutions has a higher boiling point, we need to consider the effect of the solute particles on the boiling point of the solvent.
The boiling point elevation is a colligative property, which means it depends only on the number of solute particles and not on their identity. It can be calculated using the equation:
△Tb = Kb * m
Where:
△Tb is the boiling point elevation.
Kb is the molal boiling point constant of the solvent.
m is the molality of the solute.
In this case, we are comparing two solutions:
1. A 0.35m CaCl2 solution.
2. A 0.9m urea solution.
Since CaCl2 dissociates into three particles (1 Ca²⁺ ion and 2 Cl⁻ ions) and urea does not dissociate, we can determine the effective number of solute particles for each solution:
1. For the CaCl2 solution:
Effective particles = 3 particles × molality (0.35m)
2. For the urea solution:
Effective particles = 1 particle × molality (0.9m)
Next, we need to consider the solvent. Since the solvent is not mentioned, we can assume it is water (H2O). The molal boiling point constant of water (Kb) is approximately 0.512 °C/m.
Now, we can calculate the boiling point elevation for both solutions:
1. For the CaCl2 solution:
△Tb = (0.512 °C/m) * (3 × 0.35m)
2. For the urea solution:
△Tb = (0.512 °C/m) * (1 × 0.9m)
By comparing the two calculated values of △Tb, we can determine which solution has a higher boiling point elevation and therefore a higher boiling point.
To determine which of the two aqueous solutions has a higher boiling point, we need to consider the colligative properties of solutions. Colligative properties depend on the concentration of solute particles but not their identity.
In this case, we have two aqueous solutions: 0.35m CaCl2 and 0.9m urea.
The boiling point elevation is a colligative property related to the number of solute particles present in the solution. The more solute particles present, the greater the boiling point elevation.
First, we need to determine the number of solute particles in each solution. CaCl2 dissociates into three ions when it dissolves in water (one Ca2+ ion and two Cl- ions), while urea does not dissociate and remains as a single molecule.
For the 0.35m CaCl2 solution, we have 0.35 moles of CaCl2 per liter. Since CaCl2 dissociates into three ions, the number of solute particles is 3 times the concentration of CaCl2:
Number of solute particles = 3 * 0.35 = 1.05m (moles of solute particles per liter)
For the 0.9m urea solution, we have 0.9 moles of urea per liter. However, since urea does not dissociate, the number of solute particles is equal to the concentration of urea:
Number of solute particles = 0.9m (moles of solute particles per liter)
Comparing the number of solute particles, we have 1.05m of solute particles in the CaCl2 solution and 0.9m of solute particles in the urea solution.
Since the CaCl2 solution has a higher concentration of solute particles, it will have a higher boiling point elevation compared to the urea solution. Therefore, the CaCl2 solution will have a higher boiling point than the urea solution.