Final answer:
Molality measures moles of solute per kilogram of solvent and remains constant with temperature, while molarity measures moles of solute per liter of solution and is temperature-dependent because it is based on volume.
Step-by-step explanation:
The difference between molality and molarity stems from the way they each measure the concentration of a solution. Molality is defined as the moles of solute per kilogram of solvent, while molarity is the moles of solute per liter of solution.
Molecular and Temperature Relations
Molality is particularly useful because it is not affected by temperature changes, unlike molarity. This is due to molality being dependent on mass, a property that does not change with temperature, while molarity is dependent on volume, which can expand or contract with temperature fluctuations.
Choosing Between Molarity and Molality
Chemists consider the need for accuracy in relation to temperature when deciding whether to use molality or molarity. For reactions and titrations where precise results are crucial, molality is often preferred because it provides consistent values irrespective of temperature changes, thus avoiding the inaccuracies that can occur when using molarity.
In applications involving the study of vapor pressure and temperature changes, such as boiling point elevation or freezing point depression, the use of molality offers an advantage. As molarity can vary with temperature, due to the changes in a solution’s density, using molality provides more reliable and constant measurements for these types of calculations.Final answer:
Molality measures moles of solute per kilogram of solvent and remains constant with temperature, while molarity measures moles of solute per liter of solution and is temperature-dependent because it is based on volume.
Step-by-step explanation:
The difference between molality and molarity stems from the way they each measure the concentration of a solution. Molality is defined as the moles of solute per kilogram of solvent, while molarity is the moles of solute per liter of solution.
Molecular and Temperature Relations
Molality is particularly useful because it is not affected by temperature changes, unlike molarity. This is due to molality being dependent on mass, a property that does not change with temperature, while molarity is dependent on volume, which can expand or contract with temperature fluctuations.
Choosing Between Molarity and Molality
Chemists consider the need for accuracy in relation to temperature when deciding whether to use molality or molarity. For reactions and titrations where precise results are crucial, molality is often preferred because it provides consistent values irrespective of temperature changes, thus avoiding the inaccuracies that can occur when using molarity.
In applications involving the study of vapor pressure and temperature changes, such as boiling point elevation or freezing point depression, the use of molality offers an advantage. As molarity can vary with temperature, due to the changes in a solution’s density, using molality provides more reliable and constant measurements for these types of calculations.