Question

use the information below to answer questions 13 - 16.
a mixture of 4 substances can be separated in lab according to the flow chart below. the boiling
point of water is 100°c. the boiling point of alcohol is 78°c

1. based on the separation technique used, substance a must be _.

(a) magnetic
(b) soluble in water
(c) insoluble in water
(d) insoluble in alcohol

1. what is the purpose of the final step involving substance d - boil at 78°c? this step...

(a) allows the scientist to separate the alcohol from substance d by evaporating
substance d.
(b) allows the scientist to separate the alcohol from substance d by evaporating the
alcohol.
(c) removes excess water from the mixture that was added one step prior.
(d) removes any additional impurities from the mixture.

Explanation:

13.

When water at \(30^{\circ}C\) is added and filtered, substance \(A\) is separated. Filtration is used to separate an insoluble solid from a liquid. If a substance is soluble in water, it would pass through the filter (like substances \(B\) and \(D\) which are in the filtrate after adding water). So substance \(A\) must be insoluble in water.

The boiling point of alcohol is \(78^{\circ}C\). When boiling at \(78^{\circ}C\), alcohol (which has a lower boiling - point compared to many other substances) will evaporate. Substance \(D\) remains (assuming it has a higher boiling - point than \(78^{\circ}C\)). So this step allows the scientist to separate the alcohol from substance \(D\) by evaporating the alcohol.

Answer:

C. insoluble in water

14.