Question

A beaker contains a clear, colorless liquid. If it is water, how could you determine whether it contained dissolved table salt? Do not taste it!

Short answer

To determine if the clear, colorless liquid contains dissolved table salt without tasting, perform the following steps: 1) Prepare a sample by transferring a small amount of the liquid onto a clean, dry glass slide or plate using a dropper or pipette. 2) Heat the sample gently to evaporate the liquid. 3) Observe the residue, if any, on the glass slide or plate. 4) Confirm the presence of table salt in the residue either by comparing the shape of the residue crystals under a microscope with known sodium chloride crystals or by performing a chemical test with silver nitrate solution, which will form a white precipitate if table salt is present.

Step-by-step solution

Gather the necessary materials

To perform the test for the presence of salt in the liquid, gather the following materials: - A glass beaker containing the clear, colorless liquid - A clean, dry glass slide or plate - A dropper or pipette - A source of heat (e.g., Bunsen burner, hot plate) - A spatula or glass rod

Prepare the sample

Using the dropper or pipette, extract a small amount of the liquid from the glass beaker and transfer it onto the clean, dry glass slide or plate. Please ensure you take necessary safety precautions while handling the liquid.

Evaporate the liquid

Place the glass slide or plate with the liquid sample onto the source of heat. Slowly heat the liquid to evaporate it. Be cautious during this step to avoid overheating or damaging the glass slide or plate.

Observe the residue

Once the liquid has evaporated from the glass slide or plate, inspect the surface of the glass slide or plate for any visible residue. If any residue is present, this could be an indication of dissolved table salt in the liquid.

Test the residue for table salt

To confirm if the residue is indeed table salt (sodium chloride), touch the tip of a spatula or glass rod onto the residue and observe the crystals under a microscope to compare them with reference images of sodium chloride crystals. Sodium chloride crystals are cubic in shape, colorless, and may form a stacked pattern called a "halo". Alternatively, a chemical test can be performed using a few drops of a silver nitrate solution on the residue. If the residue contains table salt, a white precipitate of silver chloride will form immediately upon adding the silver nitrate solution, which confirms the presence of dissolved table salt in the liquid.