a solution was perpared by dissolving 4.765 g of AlCl3 in enough water to give 250 mL of AlCl3?
a. how do you calculate the molarity of the solution
b. how do you calculate the osmolarity of the solution
determine the mole mass of aluminum chloride.
moles AlCl3= 4.765/molmass
Molarity= moles/.250
Osmolarity= 4 times molarity
a. To calculate the molarity of a solution, you need to know the amount of solute (in moles) and the volume of the solvent (in liters).
First, we need to convert the mass of AlCl3 into moles. The molar mass of AlCl3 is:
Aluminum (Al) : atomic mass = 27 g/mol
Chlorine (Cl) : atomic mass = 35.5 g/mol (since Cl is diatomic)
Total molar mass of AlCl3 = 27 g/mol + 3 * 35.5 g/mol = 133.5 g/mol
Now, we can calculate the moles of AlCl3:
moles of AlCl3 = mass / molar mass = 4.765 g / 133.5 g/mol = 0.0357 mol
Next, we convert the given volume from milliliters to liters:
volume = 250 mL = 250/1000 L = 0.250 L
Finally, we can calculate the molarity (M) using the formula:
Molarity (M) = moles of solute / volume of solvent
Molarity = 0.0357 mol / 0.250 L = 0.1434 M
Therefore, the molarity of the solution is 0.1434 M.
b. Osmolarity is a measure of the total concentration of solute particles in a solution. To calculate osmolarity, we need to consider the number of particles per formula unit.
In this case, AlCl3 dissociates completely into one aluminum cation (Al3+) and three chloride anions (Cl-). So, for each formula unit of AlCl3, there are four particles: one Al3+ cation and three Cl- anions.
To find the osmolarity, we multiply the number of particles per formula unit with the molarity of the solution:
Osmolarity = number of particles per formula unit * Molarity
Osmolarity = 4 particles/formula * 0.1434 M = 0.5736 osmol/L
Therefore, the osmolarity of the solution is 0.5736 osmol/L.
a. To calculate the molarity of the solution, you need to use the formula:
Molarity (M) = Number of moles of solute / Volume of solution in liters
First, you need to calculate the number of moles of AlCl3. The molar mass of AlCl3 is calculated by summing the atomic masses of each element in the compound:
Al: 26.98 g/mol
Cl: 35.45 g/mol x 3 = 106.35 g/mol
Molar mass of AlCl3 = 26.98 + 106.35 = 133.33 g/mol
Now calculate the number of moles:
Number of moles = Mass of AlCl3 / Molar mass of AlCl3
= 4.765 g / 133.33 g/mol
Next, convert the volume of solution to liters:
250 mL = 250 mL / 1000 mL/L
= 0.250 L
Now, plug these values into the formula above:
Molarity (M) = Number of moles of solute / Volume of solution in liters
= (4.765 g / 133.33 g/mol) / 0.250 L
Calculate the molarity of the solution.
b. To calculate osmolarity, you need to consider the number of particles formed when AlCl3 dissolves in water. AlCl3 dissociates into one Al3+ ion and three Cl- ions in solution, so each molecule of AlCl3 forms four particles.
First, calculate the number of moles of AlCl3 as done in part a.
Next, multiply the number of moles by the number of particles formed per mole:
Number of particles = Number of moles of AlCl3 x 4
Finally, divide the number of particles by the volume of solution in liters:
Osmolarity (osM) = Number of particles / Volume of solution in liters
Note that osmolarity is typically represented in units of osmoles per liter (osmol/L) or milliosmoles per liter (mosmol/L).