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When is it favourable to use molality instead of molarity?
Molarity (M) is a measure of the concentration of a solution in terms of moles of solute per liter of solution. Molality (m) is a measure of the concentration in terms of moles of solute per kilogram of solvent. In other words, molarity takes into account the volume of the solution, while molality takes into account the mass of the solvent.
Molarity is typically used when the temperature of the solution is not a factor, as it is a volume-based measurement. Molality, on the other hand, is used when the temperature of the solution is important, as it is a mass-based measurement. This is because changes in temperature do not affect the mass of the solvent, but they do affect the volume.
To convert from molarity to molality, you need to know the density of the solution. You can use the formula m = M / (density in g/mL) to convert from molarity to molality. To convert from molality to molarity, you need to know the molar mass of the solute. The formula for this conversion is M = (m * molar mass) / (density in g/mL).
Both molarity and molality are valid measurements of concentration, but their accuracy depends on the specific circumstances. Generally, molality is considered more accurate because it is not affected by changes in temperature. However, in some cases, molarity may be more practical to use.
No, molarity and molality are different measurements and cannot be the same for a solution. However, it is possible for a solution to have the same concentration in terms of moles per liter (molarity) and moles per kilogram (molality), but this is not always the case.