NYS Chemistry Regents Review Practice – Acids, Bases & Salts

Base your answers to questions 13, 14 and 15 on the information below:

A laboratory worker filled a bottle with a hydrochloric acid solution. Another bottle was filled with methanol, while a third bottle was filled with a sodium hydroxide solution. However, the worker neglected to label each bottle. After a few days, the worker could not remember which liquid was in each bottle. The worker needed to identify the liquid in each bottle. The bottles were labeled A, B, and C. Using materials found in the lab (indicators, conductivity apparatus, and pieces of Mg metal), the worker tested samples of liquid from each bottle. The test results are shown in the table below.

Table of Tests and Results

Test

Test Results

Bottle A

Bottle B

Bottle C

Methyl orange indicator

Yellow

Yellow

Yellow

Bromthymol blue indicator

Blue

Green

Yellow

Electrical conductivity

Conductor

Nonconductor

Conductor

Reactivity with Magnesium metal

No reaction

No reaction

Reaction

13. Using the test results, state how the worker differentiated the bottle that contained methanol from the other two bottles.

Correct Answer:

Methanol does not conduct an electric current and the test result for bottle B shows that the contents in Bottle B is a nonconductor, hence it can be inferred that bottle B contains methanol.

Also, Bromthymol blue tests blue in a base and yellow in an acid, so bottle B must be methanol.

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