what is the molality of 18 g NaCl in 200 g of H2O?

See Destiny et al.

OH YEAAAH

To find the molality (m) of a solution, you need to know the amount of solute (in moles) and the mass of the solvent (in kilograms). Molality is defined as the number of moles of solute per kilogram of solvent.

In this case, the solute is 18 g of NaCl, and the solvent is 200 g of H2O.

Step 1: Convert the mass of solute to moles
To convert the mass (in grams) of the solute (NaCl) to moles, you need to divide the given mass by the molar mass of NaCl. The molar mass of NaCl is 58.44 g/mol.

Number of moles of NaCl = mass of NaCl (g) / molar mass of NaCl (g/mol)
Number of moles of NaCl = 18 g / 58.44 g/mol

Step 2: Convert the mass of the solvent to kilograms
The mass of the solvent (H2O) is given as 200 g. To convert it to kilograms, you need to divide by 1000.

Mass of H2O (kg) = mass of H2O (g) / 1000
Mass of H2O (kg) = 200 g / 1000

Step 3: Calculate the molality
Now that you have the number of moles of NaCl and the mass of H2O in kilograms, you can calculate the molality using the formula:
Molality (m) = moles of solute / mass of solvent (in kg)

Molality (m) = number of moles of NaCl / mass of H2O (kg)

Substituting the values:
Molality (m) = (18 g / 58.44 g/mol) / (200 g / 1000)

Molality (m) = 0.3083 mol / 0.2 kg

Molality (m) = 1.5415 mol/kg

Therefore, the molality of 18 g NaCl in 200 g of H2O is approximately 1.54 mol/kg.