Calculate the molality of 48.2 percent by mass KBr solution?
48.2g of KBr/(100g-48.2g)*(mole/119.002 g)= moles of KBr/Solvent in g
moles of KBr/Solvent in g*(1g/10^-3kg)= molality of solution <=== 3 Sig figs
Ah, molality calculations, my expertise! To determine the molality of a solution, we need to know the mass of the solute (KBr) and the mass of the solvent (usually water).
Now, let's assume we have 100g of the solution. This means that there are 48.2g of KBr and 51.8g of the solvent (since 100 - 48.2 = 51.8).
To find the molality, we must find the moles of solute (KBr) and divide it by the mass of the solvent (in kg).
The molar mass of KBr is approximately 119 g/mol. Thus, we have:
Moles of KBr = (48.2g / 119 g/mol) = 0.4046 mol
To convert the mass of the solvent to kg, divide by 1000:
Mass of solvent (in kg) = 51.8g / 1000 = 0.0518 kg
Finally, we can calculate the molality:
Molality = Moles of solute / Mass of solvent (in kg)
Molality = 0.4046 mol / 0.0518 kg ≈ 7.8 mol/kg
So, the molality of the 48.2 percent by mass KBr solution is approximately 7.8 mol/kg. Now that's some salty chemistry humor for you!
To calculate the molality of a solution, you need to know the mass of the solute and the mass of the solvent. In this case, you have a 48.2% by mass KBr solution.
1. Suppose you have 100 grams of the solution. This means that 48.2 grams of the solution is KBr.
2. Using the molar mass of KBr, which is about 119 grams/mol, you can calculate the number of moles of KBr present in the solution.
Number of moles of KBr = Mass of KBr / Molar mass of KBr
= 48.2 g / 119 g/mol
≈ 0.405 moles
3. Similarly, suppose you have 100 grams of the solvent (water in most cases). This means that 100 - 48.2 = 51.8 grams of the solution is water.
4. Calculate the mass of water in kilograms (to use in the molality formula).
Mass of water = 51.8 g / 1000
= 0.0518 kg
5. Finally, use the molality formula:
molality = moles of solute / mass of solvent (in kg)
= 0.405 moles / 0.0518 kg
≈ 7.81 mol/kg
Therefore, the molality of the 48.2% by mass KBr solution is approximately 7.81 mol/kg.
To calculate the molality of a solution, you need to know the mass of the solute and the mass of the solvent. In this case, the solute is KBr (potassium bromide) and the solvent is the solution itself.
First, let's determine the mass of the solute:
Given that the solution is 48.2% by mass KBr, we can conclude that 48.2 grams of the solution contains 100% KBr. Therefore, to find the mass of KBr in the solution, we can multiply the total mass of the solution by the mass percent of KBr:
Mass of KBr = (48.2 grams of solution) × (48.2% KBr) = 48.2 grams × (0.482) = 23.24 grams
Next, let's determine the mass of the solvent:
Since the solution is a 48.2% by mass KBr solution, the remaining percentage (100% - 48.2% = 51.8%) represents the solvent (water in this case). Therefore, the mass of the solvent can also be obtained by multiplying the total mass of the solution by the remaining percentage:
Mass of solvent = (48.2 grams of solution) × (51.8% solvent) = 48.2 grams × (0.518) = 24.966 grams
Now that we know the mass of the solute (KBr) and the solvent, we can calculate the molality (m):
Molality (m) = (moles of solute) / (kilograms of solvent)
First, let's calculate the moles of solute:
Moles of solute = (mass of solute) / (molar mass of KBr)
The molar mass of KBr can be determined by adding the atomic masses of potassium (K) and bromine (Br):
Molar mass of KBr = (atomic mass of K) + (atomic mass of Br) = 39.10 g/mol + 79.90 g/mol = 119.00 g/mol
Moles of solute = 23.24 grams / 119.00 g/mol = 0.1952 mol
Finally, we can calculate the molality:
Molality (m) = 0.1952 mol / (24.966 grams / 1000) kg = 7.817 mol/kg (rounded to 4 decimal places)
Therefore, the molality of the 48.2% by mass KBr solution is 7.817 mol/kg.