Molality is preferred over molarity in handling solutions in chemistry laboratory becausea)Molality changes with pressureb)Molarity changes with temperaturec)Molality changes with temperatured)Molarity changes with pressureCorrect answer is option 'B'. Can you explain this answer?

Question

Answer

Molarity is inversely proportional to volume . and
we know that from charles law i.e. volume is directly proportional to temperature.This implies that molarity is inversely proportional to temperature. Whereas molality is independent of temperature. Hence;option B is true.

Answer

Molarity is number of moles per unit volume of the solution and molality is number of moles per unit mass of solvent. Volume is temperature dependent where as mass is constant at all temperatures. So, molality remains constant but molarity changes with temperature. Hence , molality is preferred over molarity.

Answer

Understanding Molality and Molarity
In chemistry, the handling of solutions often requires precision, and the choice between molality and molarity is crucial.
Definition of Molarity
- Molarity is defined as the number of moles of solute per liter of solution.
- It is expressed in moles per liter (mol/L).
Definition of Molality
- Molality is defined as the number of moles of solute per kilogram of solvent.
- It is expressed in moles per kilogram (mol/kg).
Temperature Dependence of Molarity
- Molarity is sensitive to temperature changes.
- As temperature increases, the volume of the solution can expand, leading to a decrease in molarity because the same number of moles is now contained in a greater volume.
- This fluctuation can affect calculations and experimental results.
Advantages of Molality
- Molality remains constant regardless of temperature since it is based on mass rather than volume.
- This stability is particularly advantageous in experiments involving temperature variations, such as calorimetry.
Pressure Influence
- Both molality and molarity are generally unaffected by pressure; however, for most practical laboratory scenarios, molarity is more likely to be influenced by temperature changes.
Conclusion
- The preference for molality over molarity in many laboratory contexts stems from the temperature stability of molality.
- Using molality ensures that calculations remain accurate and consistent, especially when temperature fluctuations occur during experiments.
By understanding these concepts, chemists can select the most appropriate method for measuring concentrations in their work.

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