Question

In the procedure for determining the volume of the flask used for the molar mass determination, two methods were outlined. Briefly describe these methods and explain which method will give a more precise determination of the volume.

A) Method 1: Filling the flask to the brim; Method 2: Filling the flask gradually. Method 2 will give a more precise determination of the volume.
B) Method 1: Filling the flask gradually; Method 2: Filling the flask to the brim. Method 1 will give a more precise determination of the volume.
C) Method 1: Measuring the flask's diameter; Method 2: Measuring the flask's height. Method 2 will give a more precise determination of the volume.
D) Method 1: Using a ruler to measure the flask's volume; Method 2: Using a graduated cylinder to measure the flask's volume. Method 2 will give a more precise determination of the volume.

Answer 1

The most precise method for determining the volume of a flask for molar mass determination involves filling the flask gradually with a solvent up to the calibration mark using graduated laboratory equipment, such as a pipette or a graduated cylinder.

Step-by-step explanation:

The question pertains to the methods used for determining the volume of a flask in an experiment to calculate a substance's molar mass. Among the options provided, the correct one is not explicitly given, but we can infer the most precise method based on standard laboratory techniques. When filling a volumetric flask for precise measurements, a scientist would use a graduated cylinder or any other graduated equipment to add a solvent to a specific mark on the flask, ensuring accuracy. Filling the flask gradually allows for careful adjustment of the fluid level to the calibration mark. On the other hand, measuring the flask's physical dimensions (diameter and height) or using non-graduated means, like a ruler, is less precise for determining volume, especially since flasks can have irregular shapes or may not be precisely calibrated in height and diameter.

Therefore, the most precise method for volume determination is to fill the flask gradually using calibrated apparatus such as a pipette or graduated cylinder, ensuring that the solvent reaches the fill line accurately which is important for calculations involving molar mass determination. Absolute precision in volume measurement is crucial, as any small error can lead to significant discrepancies when determining the concentration or molar mass of a solution. Thus, the method of filling the flask to the brim is less precise due to the possibility of overfilling and the difficulty of ensuring an exact level at the very top of the flask without spilling.