Calculate the osmolarity of a solution that contains 0.1 M urea, 0.2 M NaCl, and 0.5 M CaCl2. Assume urea does not ionize and NaCl and CaCl2 ionize completely
Osmolarity measures the number of particles in a solution. For ionized compounds, each ion counts as one.
For example,
NaCl=Na+ + Cl- counts as 2 particles
So the total osmolarity
=0.1*1 + 0.2*2 + 0.5*3
=2 osm/l.
To calculate the osmolarity of a solution, we need to calculate the total concentration of solute particles in the solution.
Since urea does not ionize, its concentration remains the same. So, the concentration of urea is 0.1 M.
NaCl completely ionizes into Na+ and Cl- ions. This means that 0.2 M of NaCl will contribute 0.2 M of Na+ ions and 0.2 M of Cl- ions.
Similarly, CaCl2 completely ionizes into Ca2+ and 2 Cl- ions. This means that 0.5 M of CaCl2 will contribute 0.5 M of Ca2+ ions and 1 M of Cl- ions (2 * 0.5 M).
Therefore, the osmolarity of the solution can be calculated by adding up the concentrations of all the solute particles:
Osmolarity = urea concentration + Na+ concentration + Cl- concentration
= 0.1 M + 0.2 M + 0.2 M + 1 M
= 1.5 M
So, the osmolarity of the solution is 1.5 M.
To calculate the osmolarity of a solution, you need to consider the number of particles (ions or molecules) in the solution. Osmolarity is a measure of the total concentration of solute particles in a solution.
Firstly, we need to determine the number of particles each solute contributes to the solution. Since the problem states that urea does not ionize, it remains as one molecule. NaCl dissociates into one sodium ion (Na+) and one chloride ion (Cl-). On the other hand, CaCl2 dissociates into one calcium ion (Ca2+) and two chloride ions (2Cl-).
Now, let's calculate the osmolarity:
For urea (0.1 M):
Urea does not ionize, so we consider it as one molecule contributing to osmolarity.
Osmolarity = 0.1 M * 1 = 0.1 osM (osmolarity)
For NaCl (0.2 M):
Each NaCl molecule dissociates into one sodium ion (Na+) and one chloride ion (Cl-). Therefore, each mole of NaCl contributes two particles to the osmolarity.
Osmolarity = 0.2 M * 2 = 0.4 osM
For CaCl2 (0.5 M):
Each CaCl2 molecule dissociates into one calcium ion (Ca2+) and two chloride ions (2Cl-). Therefore, each mole of CaCl2 contributes three particles to the osmolarity.
Osmolarity = 0.5 M * 3 = 1.5 osM
Finally, we sum up the contributions from each solute to find the total osmolarity:
Total osmolarity = osmolarity of urea + osmolarity of NaCl + osmolarity of CaCl2
Total osmolarity = 0.1 osM + 0.4 osM + 1.5 osM = 2 osM
Therefore, the osmolarity of the solution containing 0.1 M urea, 0.2 M NaCl, and 0.5 M CaCl2 is 2 osM.