Final answer:
The molality of a solution of 1.2 g of HCl in 750 g of solvent is 0.0439 molal, calculated by dividing the number of moles of HCl by the mass of the solvent in kilograms.
Step-by-step explanation:
To calculate the molality of a solution, you would first need to divide the mass of the solute by its molar mass to find the number of moles present. For hydrochloric acid (HCl), the molar mass is 36.46 g/mol. So, for 1.2 g of HCl:
Number of moles of HCl = mass of HCl (g) / molar mass of HCl (g/mol) = 1.2 g / 36.46 g/mol = 0.0329 moles
Next, molality is defined as moles of solute per kilogram of solvent. Since we have 750 g of solvent, we convert this to kilograms:
Mass of solvent in kg = 750 g / 1000 g/kg = 0.75 kg
Finally, calculate the molality:
Molality (m) = moles of solute / kg of solvent = 0.0329 moles / 0.75 kg = 0.0439 molal