The identification labels fell off three test tubes, each containing a colorless

Question

The identification labels fell off three test tubes, each containing a colorless solution. A student knew that one of the test tubes contained 0.1 HCl solution, another contained 0.1M NaOH solution, and the third contained 0.1% phenolphthalein indicator solution. To determine the identity of each solution, the temporarily the tubes, and The student mixed the label solutions in various combinations, recording all observations in the table below. Determine which original label should be attached to each of the test tubes. Even people who are not familiar with the study of chemistry use the expression, "the litmus test, when referring to a test that produces an unquestionable result. On the basis of your experimental results, can you conclude that using litmus paper provides a "litmus test" for determining whether a solution is acidic or basic? Briefly explain.

Explanation / Answer

First we need to understand in what condition Phenophthalein indicator changes the color.

pH = 0 - 8.2 this indicator shows colorless (in acidic to near neutral)

pH = 8.212.0 this indicator shows red color (in basic solution)

The given conditions are:

A + B gives solution D a red color solution means D is a basic solution.

So either A or B is base or indicator!

D + C gives colorless solution E, means it is an acidic solution.

So C is neutralizing D (a basic solution) and making it acidic, hence C is Acid.

E + B gives makes and acidic solution to basic solution (color is changes back to red), means B is the base.

So far, C is acid B is Base and hence, remaning A is indicator.

3)

Litmus test is the test carried out to test if given solution is acidic or basic. (not pricise indication of pH but an idea of acidity or basicity). Although the test is not pricise but it is an important test in chemical labs. It requirers very less sample (a drop would be enough). It gives results in seconds. It does not require any special set-up. Thus these advantages makes litmus test important in Chem labs.

Red litmus paper is used to test the base. When a red litmus paper is immersed in a basic solution, the red litmus paper turns blue indicating the given solution as basic.

And blue litmus paper is used to test an acidic solutions. When a blue litmus paper immersed in an acidic solution, the litmus paper turns red from blue indicating acidic nature of the solution.

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