Question

Which of the following is dependent on temperature?
A. Weight percentage
B. molality
C. molarity
D. mole fraction

Answer 1

Hint: According to the gas law the volume is a function of temperature at constant pressure. Volume depends upon the temperature. On changing the temperature volume will also change.so, the concentration term which depends upon the volume will be affected by temperature change.

Complete step by step answer:
Weight percentage, molality, molarity and mole fraction all terms are used to define the concentrations.
The formula of weight percentage is as follows:
${\text{weight percentage}}\,{\text{ = }}\,\dfrac{{{\text{weight}}\,{\text{of}}\,{\text{solute}}}}{{{\text{weight}}\,{\text{of}}\,{\text{solution}}}} \times 100$
The formula of molality is as follows:
\[{\text{molality}}\,{\text{ = }}\,\dfrac{{{\text{Moles}}\,{\text{of}}\,{\text{solute}}}}{{{\text{kg}}\,{\text{of}}\,{\text{solvent}}}}\]
So, the formula of molarity is as follows:
${\text{Molarity}}\,{\text{ = }}\,\dfrac{{{\text{Moles}}\,{\text{of}}\,{\text{solute}}}}{{{\text{Litter}}\,{\text{of}}\,{\text{solution}}}}$
The formula of mole fraction is as follows:
${\text{Mole fraction}}\,{\text{ = }}\,\dfrac{{{\text{Moles}}\,{\text{of}}\,{\text{component}}}}{{{\text{total mole of the mixture}}}}$
The ideal gas equation is as follows:
${\text{PV = nRT}}$.
Where,
$P$ is the pressure.
V is the volume.
$n$ is the number of moles.
R is the gas constant.
T is the temperature
The temperature is directly proportional to the volume at constant pressure according to the ideal gas equation. So, the changing temperature volume will change.

Molarity is the function of the mole of solute and volume of the solution so, molarity will be affected by the change in temperature.
Mole is determined by dividing the mass by molar mass. So, the term mole in molality and mole fraction can be replaced with mass and molar mass.
The formula of mole is as follow:
\[{\text{mole}}\,{\text{ = }}\,\dfrac{{{\text{Mass}}}}{{{\text{molar mass}}}}\]
\[{\text{molality}}\,{\text{ = }}\,\dfrac{{{\text{Mass/ molar mass}}\,{\text{of}}\,{\text{solute}}}}{{{\text{kg}}\,{\text{of}}\,{\text{solvent}}}}\]
${\text{Mole fraction}}\,{\text{ = }}\,\dfrac{{{\text{Mass/ molar}}\,{\text{mass}}\,{\text{of}}\,{\text{component}}}}{{{\text{total mole of the mixture}}}}$
So, Weight percentage, molality and mole fraction all are the function of weight. Weight is independent of the temperature.

Therefore option (C) molarity is correct.

Note:
Weight percentage is defined as the percentage weight of solute divided by the weight of the solution. Molality is defined as the amount of solute dissolved in an amount of solvent. The amount of solute is taken in the form of a mole and the amount of solvent is taken as per kilogram. Molarity is defined as the amount of solute dissolved in a volume of solution. The amount of solute is taken in the form of a mole and the volume of the solution is taken as per litre. Mole fraction is defined as the mole of a component divided by the total mole of the mixture.