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 a solid yellow cube with a total mass of 50.0 g. The cube is ground to a fine orange powder and added to a 500 ml beaker full of water. The beaker is stirred vigorously. Some of orange powder settles to the bottom of the beaker, and some rises to the top and floats on the water. When the powder at both the bottom and the top of the beaker is filtered out, dried, and weighed, the total mass is measured to be 50.1 g. • Sample B is 100 mL of a clear liquid. The density of the liquid is measured, and turns out to be 0.77 g/mL. The liquid is then heated in a flask until it boils. The vapor that rises off the bolling 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. Opure substance х Is sample A made from a pure substance or a mixture? If the description of the substance and the outcome of the experiment isn't enough to decide, choose "can't decide." mixture O can't decide) O pure substance Is sample B made from a pure substance or a mixture? If the description of the substance and the outcome of the experiment isn't enough to decide, choose "can't decide mixture (can't decide)

Answer 1

Answer:

Sample A is  a pure substance

Sample B is a mixture

Explanation:

We are told that the when the yellow solid, sample A is ground it turned to orange colour  and was then dissolved. Some part of the solid settled out at the bottom of the beaker while some part floated on top of the water. 50g of the solid was dissolved and 50.1g of the solid was recovered.

This implies that the substance is pure since the mass dissolved was almost the same mass recovered. The 0.1g addition in mass may result from incomplete drying of the solid.

For sample B, the distillation of the sample of density 0.77 g/ml left a fraction in the beaker with density 1.04 g/ml indicating that the substance is a mixture. Different components of a mixture possess different densities.