A forensic chemist is given samples of four unidentified solutions. The identities of these solutions could
affect the outcome of a court case that involved someone being electrocuted. The chemist has reason to
believe that the four solutions are sodium chloride, NaCl (aq), hydrochloric acid, HCI (aq), ethanol, C₂H5OH
(aq), a base, Ba(OH)₂ (aq).
The chemist designs an experiment to identity the chemicals. They dissolve each sample in water and test
the solution with a conductivity apparatus and litmus paper.
(Acidic solutions turn blue litmus paper red. Basic solutions turn red litmus paper blue.)

A. What are the identities of the four substances, labeled 1-4 in
Table 3. Evidence

Solutions.

Water
1
2
3
4

Electrical Conductivity
None
High
High
None
High

Litmus
No change
No change
Blue to red
No change
Red to blue
B. Which of the solutions (1, 2, 3, and/or 4) could not have been involved in an electrocution? Explain
your answer.