What is the molality of a solution composed of 2.55g of acetone (CH3)2CO, dissolved in 200.g of water?

mols acetone = grams/molar mass = ?

m = mols acetone/0.200 g solvent = ?

To find the molality of a solution, you need to know the amount of solute (in moles) and the mass of the solvent (in kilograms).

First, let's find the number of moles of acetone (CH3)2CO in the solution. The molar mass of acetone is:

C: 12.01 g/mol x 3 = 36.03 g/mol
H: 1.01 g/mol x 6 = 6.06 g/mol
O: 16.00 g/mol = 16.00 g/mol

Total molar mass of acetone = 36.03 g/mol + 6.06 g/mol + 16.00 g/mol = 58.09 g/mol

To convert the mass of acetone to moles, divide the given mass by the molar mass:

2.55g / 58.09 g/mol = 0.0439 mol

Next, let's find the mass of water in kilograms:

200. g of water = 200. g / 1000 = 0.2 kg

Finally, use the moles of solute and mass of solvent to calculate the molality:

Molality (m) = moles of solute / mass of solvent in kg
= 0.0439 mol / 0.2 kg
≈ 0.22 mol/kg

Therefore, the molality of the solution is approximately 0.22 mol/kg.