# Which of the following is temperature independent?

34 views

closed
Which of the following is temperature independent?
1. Molality
2. Molarity
3. Normality
4. All of these

by (54.3k points)
selected

Correct Answer - Option 1 : Molality

Concept:

Molality:

• It is defined as the number of moles of solute per kilogram of solvent.
• Unit of Molality is the mole. Kg-1.

${\rm{Molality}} = \frac{{{\rm{Moles\;of\;Solute}}}}{{{\rm{Kilogram\;of\;solvent}}}}$

Molarity:

• It is defined as the moles of a solute per liters of a solution.
• It is also known as the molar concentration of a solution.
• The unit of Molarity is the mole. lit-1.
• It is given by:

$\rm \frac{{Number\;of\;moles\;of\;solute}}{{Mass\;of\;solvent\left( {in\;g} \right)}} \times 1000$

• Normality:
• It is defined as the number of grams equivalent per liter of solution.
• Also known as equivalent concentration.

${\rm{Normality}} = \frac{{{\rm{Gram\;equivalents}}}}{{{\rm{volume\;of\;solution\;in\;liter}}}}$

Explanation:

• Volume is dependent on temperature. When we increase the temperature, a liquid expands and its volume increases.
• When we decrease the temperature, keeping the pressure constant, the volume of a liquid decreases.
• Thus we can say that volume is directly proportional to temperature.
• So, the concentration terms having volume terms in them will also be dependent on temperature.
• We see that Molarity and Normality are the terms that are dependent on volume.
• Molarity and Normality are both inversely proportional to the volume and are temperature dependent.
• On the other hand, we know that mass does not depend on temperature, so Molality which is the number of moles per kg of a solvent is independent of temperature.

Hence, Molality is temperature independent.