Two beakers are on a laboratory bench. one beaker contains 1.0 m hcl and the other contains tap water. what could an experimenter do to distinguish the acid solution from the tap water?

a. drop a piece of magnesium in each solution.
b. drop a piece of copper in each solution.
c. dip a piece of red litmus paper in each solution.
d. smell the two solutions.

C. Dip a piece of red litmus paper in each solution

Explanation:

In case you have a solution of HCl 1M and tap water, for the second case, it´s probably that pH will be in a around 7 (and a bit above 7,this is, a bit alkaline)

A red litmus paper is a piece (or strip) of paper, which may help to determine the pH of a solution: it will turn into blue color when it is dipped in a alkaline solution (this is, with a pH > 7) or will turn into red colour when it is dipped in an acid solution (this is, with pH < 7)

If using copper, this metal has no reaction to an acid like HCl, since copper has a normal reduction potential higher that hydrogen (from HCl), for which it is difficult to the H⁺ to “steal” electrons from Copper (this is, both Cu and H⁺ will not easily react)

Lastly, when dropping a piece of magnesium into water and HCL, this metal will react as following:

Mg⁰ + 2H₂O → Mg(OH)₂(ac) + H₂  (g)

Mg⁰ + HCl → MgCl₂(ac) + H₂(g)

So both water and HCL will produce a gas (H₂) and this will not help us to differentiate them between each other

So, the best and quick method to distinguish tap water from HCl is with a red litmus paper

C. Dip a piece of red litmus paper in each solution.

Explanation:

HCl is an acid. An acid is a chemical species that donates protons or hydrogen ions and accepts electrons. They are sour to taste.

Using a blue litmus paper we can distinguish the both. The one which turns blue to red is the acidic solution that is HCl.

As boiling point of HCl is lower than water. If both are heated which ever solution boils faster is the acid.

By using an indicator like Phenolphthalein or cabbage juice. the cabbage juice will turn red if mixed with acid and light green when mixed with water because generally water is little basic in nature. The correct option is C"