Question

read the descriptions below of two substances and an experiment on each. decide whether the result of the experiment tells you the substance is a pure substance or a mixture, if you can.

sample a is 100 ml of a clear liquid. the liquid is heated in a flask until it boils. the vapor that rises off the boiling liquid is collected for 10 minutes and cooled until it condenses into a separate beaker. the density of the liquid that remains in the flask is then measured, and turns out to be 1.04 g/ml. the density of the liquid that boiled off turns out to be 1.05 g/ml.

sample b is a solid yellow cube with a total mass of 50.0 g. the cube is divided into two smaller 25.0 g subsamples, and the volume of each subsample is measured. the volume of the first is 48.2 cm³ and the volume of the second is 58.1 cm³. when the experiment is repeated with a new 50.0 g sample, the volume of the two 25.0 g subsamples is 52.2 cm³ and 50.8 cm³.

is sample a made from a pure substance or a mixture? if the description of the substance and the outcome of the experiment isnt enough to decide, choose \cant decide\. pure substance mixture (cant decide)

is sample b made from a pure substance or a mixture? if the description of the substance and the outcome of the experiment isnt enough to decide, choose \cant decide\. pure substance mixture (cant decide)

Explanation:

Step1: Analyze sample A

A pure substance has a constant density. Since the density of the liquid that boiled off (1.05 g/mL) is different from the density of the liquid remaining in the flask (1.04 g/mL), sample A is a mixture.

Step2: Analyze sample B

For a pure substance, the ratio of mass to volume (density) should be consistent for equal - mass subsamples. The volumes of equal - mass subsamples of sample B vary significantly in different trials, indicating that sample B is a mixture.

Answer:

Is sample A made from a pure substance or a mixture? mixture
Is sample B made from a pure substance or a mixture? mixture