Find the Molality and Molarity of a solution where 1.0g of NaCl was dissolved in 100mL of rubbing alcohol (the density of the alcohol is 0.78 g/mL).
Not sure what steps to use to find Molarity and Molality....
100 mL alcohol has what mass?
mass = volume x density = 100 x0.78 = 780g or 0.780 kg.
mols 1.0 NaCl = 1.0/molar mass NaCl.
m = mols/kg solvent = ?
In order to calculate M you should know the density of the solution and you don't have that. I know the density of the alcohol is given but that isn't the density of the solution. To work the problem we must assume the volume of the soln is the same as the volume alcohol added. It won't be but it will be close.
Then M = mols NaCl/0.1L = ?
To find the molarity and molality of a solution, you need to use the formulas:
1. Molarity (M) = moles of solute / volume of solution in liters
2. Molality (m) = moles of solute / mass of solvent in kilograms
Here's how you can calculate the molarity and molality of the given solution:
Step 1: Convert the mass of NaCl to moles.
- The molar mass of NaCl (sodium chloride) is 58.44 g/mol.
- Use the formula: moles = mass / molar mass.
- Substituting the values, moles = 1.0 g / 58.44 g/mol.
Step 2: Convert the volume of solution to liters.
- The volume of the solution is given as 100 mL.
- To convert to liters, divide the volume by 1000 (since 1 L = 1000 mL).
- Substituting the values, volume = 100 mL / 1000 mL/L.
Step 3: Calculate the molarity.
- Use the formula: M = moles / volume.
- Substituting the values, M = (1.0 g / 58.44 g/mol) / (100 mL / 1000 mL/L).
Step 4: Convert the mass of the alcohol to kilograms.
- The mass of the alcohol can be calculated using the density and volume.
- Mass = density * volume.
- Substituting the values, mass = 0.78 g/mL * 100 mL.
Step 5: Convert the mass of the alcohol to kilograms.
- Since 1 kg = 1000 g, divide the mass by 1000.
- Substituting the values, mass = (0.78 g/mL * 100 mL) / 1000 g/kg.
Step 6: Calculate the molality.
- Use the formula: m = moles / mass.
- Substituting the values, m = (1.0 g / 58.44 g/mol) / [(0.78 g/mL * 100 mL) / 1000 g/kg].
By following these steps, you can find both the molarity (M) and molality (m) of the given solution.