calcululate the molality of CsCl in a 8% by mass aqueous solution. answer in units of m

8% WHAT? w/v perhaps.

8% w/v means 8g CsCl in 100 mL soln.
8g/molar mass CsCl = moles.
Then m = moles/kg solvent. But you don't have the density listed so you don't know the mass of the solvent.

To calculate the molality of CsCl in a 8% by mass aqueous solution, you need the molar mass of CsCl and the mass of CsCl present in the solution.

1. Find the molar mass of CsCl:
- The molar mass of Cs (Cesium) is approximately 132.91 g/mol.
- The molar mass of Cl (Chlorine) is approximately 35.45 g/mol.
- Therefore, the molar mass of CsCl is 132.91 g/mol + 35.45 g/mol = 168.36 g/mol.

2. Determine the mass of CsCl in the solution:
- In an 8% by mass solution, the mass percent of CsCl is 8 g per 100 g of solution. This means there are 8 g of CsCl in a 100 g solution.
- Let's assume we have 1000 g (1 kg) of the solution for easier calculations. In this case, the mass of CsCl would be (8 g / 100 g) x 1000 g = 80 g.

3. Calculate the molality:
- Molality is defined as the number of moles of solute (CsCl) per kilogram of solvent (water) in the solution.
- We need to convert the mass of CsCl to moles using its molar mass.
- Moles of CsCl = Mass of CsCl / Molar mass of CsCl = 80 g / 168.36 g/mol = 0.4753 mol.
- Since we're assuming 1 kg of water, the molality would be 0.4753 mol / 1 kg = 0.4753 m (mol/kg).

Therefore, the molality of CsCl in an 8% by mass aqueous solution is 0.4753 m (mol/kg).