5. The density of a solution of 3.69 g KCI in 21.70 g H2O is
1.11 g/mL. Calculate the molality of KCI in the solution.
m = molality = mols KCl/kg solution
mols KCl = g/molar mass = 3.69/74.6 = approx 0.05
m = 0.05/0.02170 = ?
The density of a solution of 3.69 g KCI in 21.70 g Hâ‚‚O is 1.11 g/mL. Calculate the molality of KCI in the solution.
Well, this seems like a job for the Clown Bot! Don't worry, I'll crunch those numbers for you.
First, we need to find the volume of the solution. To do this, we divide the mass of the solution (21.70 g H2O) by its density (1.11 g/mL):
Volume of solution = Mass of solution / Density = 21.70 g / 1.11 g/mL
Now, we'll subtract the mass of water (21.70 g) from the mass of the solution (3.69 g + 21.70 g) to find the mass of KCI:
Mass of KCI = Mass of solution - Mass of water = (3.69 g + 21.70 g) - 21.70 g
Finally, we divide the mass of KCI by the molar mass of KCI to find the number of moles:
Number of moles of KCI = Mass of KCI / Molar mass of KCI
And there you have it, the molality of KCI in the solution. It's Neverland time! ...I mean, calculation time.
To calculate the molality of KCl in the solution, we need to first calculate the mass of KCl and the mass of water.
Given:
Mass of KCl (m1) = 3.69 g
Mass of water (m2) = 21.70 g
Density of solution = 1.11 g/mL
The formula for density is density = mass/volume.
We can rearrange this formula to find the volume:
Volume of solution = mass/density
The volume of the solution is the sum of the volumes of KCl and water:
Volume of solution = Volume of KCl + Volume of water
Since we know the density of the solution and mass, we can calculate the volume of the solution.
Volume of solution = (m1 + m2) / density
Substituting the given values:
Volume of solution = (3.69 g + 21.70 g) / 1.11 g/mL
Volume of solution = 25.39 g / 1.11 g/mL
Volume of solution = 22.83 mL
Now that we know the volume of the solution, we can calculate the molality.
Molality = (moles of solute) / (mass of solvent in kg)
First, let's calculate the moles of KCl:
Molar mass of KCl = 74.5513 g/mol
Moles of KCl = Mass of KCl / Molar mass of KCl
Moles of KCl = 3.69 g / 74.5513 g/mol
Moles of KCl = 0.0495 mol
Next, convert the mass of water to kg:
Mass of water in kg = 21.70 g / 1000
Mass of water in kg = 0.0217 kg
Now we can calculate the molality:
Molality = 0.0495 mol / 0.0217 kg
Molality = 2.279 mol/kg
Therefore, the molality of KCl in the solution is 2.279 mol/kg.
To calculate the molality of KCI in the solution, we first need to determine the amount of KCI in moles and the mass of water in kilograms.
Step 1: Calculate the number of moles of KCI
The molar mass of KCI (potassium chloride) is given by:
Atomic mass of K (39.1 g/mol) + Atomic mass of Cl (35.45 g/mol) = 74.55 g/mol
To find the number of moles of KCI, divide the mass of KCI by its molar mass:
Number of moles of KCI = 3.69 g / 74.55 g/mol = 0.0496 mol KCI
Step 2: Convert the mass of water to kilograms
The given mass of water is 21.70 g. To convert it to kilograms, divide by 1000:
Mass of water = 21.70 g / 1000 = 0.0217 kg
Step 3: Calculate the molality of KCI
Molality (m) is defined as the number of moles of solute per kilogram of solvent. Therefore, we divide the moles of KCI by the mass of water in kilograms:
Molality of KCI = 0.0496 mol / 0.0217 kg = 2.28 mol/kg