Answer:
[CaCl₂·2H₂O] = 1.43 m
Explanation:
Molality is mol of solute / kg of solvent.
Mass of solvent = 40 g
Let's convert g to kg → 40 g / 1000 = 0.04 kg
Let's determine the moles of solute (mass / molar mass)
8.43 g / 146.98 g/mol = 0.057 mol
Molality = 0.057 mol / 0.04 kg → 1.43
You can't usually just use a single spectrum line to confirm the identity of an element because there are cases that the emission line id not clearly defined. When the emission line is very weak compared to surrounding noise, in which case the more datapoints you have to build up confidence for the existence of a particular emission spectra, the better.
