i combined agno3 with 25ml of tap water, and it turned faint blue
which ion is present in trace amounts in tap water but not in distillied water? explain. what is the source of the ion in the tap water?
I would have expected a white turbidity due to AgCl (2AgNO3 + Cl2 ==> 2AgCl(s)). The source of the ppt is from the small amount of chlorine used in most city water systems to purify water for purposes of drinking. The faint blue color you saw could be due to two things but I have no idea which one it is. I would need more information for that.
1. AgCl decomposes in light to form Ag(s) + Cl2 and the Ag(s) metal is colloidal and violet in color.
2. The AgCl CAN be blue if the size of the solid particles is right.
I suspect #1 is more probable than #2.
The Cl2 reacts with water to form the Cl^- and OCl^-. It's the Cl^- that reacts with the Ag^+ to form AgCl(s).
To identify which ion is present in trace amounts in tap water but not in distilled water, we need to understand the potential sources of ions in tap water. Tap water can contain various dissolved ions derived from natural sources, water treatment processes, and the infrastructure it passes through.
To determine the specific ion, we can utilize a process called qualitative analysis. This involves performing specific chemical tests to identify the presence of different ions in a solution. Let's go through the steps to find the answer:
1. Prepare a sample of distilled water: Take a sample of distilled water, approximately 25 mL, in a clean container. This will serve as a control to compare the results.
2. Prepare a sample of tap water: Take another sample of tap water, approximately 25 mL, in a separate clean container.
3. Add silver nitrate (AgNO3) solution to both samples: Take a small amount of silver nitrate (AgNO3) solution and add it to both the distilled water and tap water samples. AgNO3 reacts with certain ions to form insoluble precipitates, indicating the presence of those ions.
4. Observe the color changes: After adding the AgNO3 solution, observe any color changes that occur in both samples. Note any distinct color changes or precipitate formations.
Based on your observation that the tap water turns faint blue, it suggests the presence of the chloride ion (Cl-) in trace amounts. When AgNO3 is added to tap water, it reacts with the small concentration of chloride ions to form a pale blue precipitate called silver chloride (AgCl). This color change does not occur when AgNO3 is added to distilled water since distilled water does not contain significant amounts of chloride ions.
The source of chloride ions in tap water can vary. It could be derived from natural sources, such as minerals in the soil and rocks that water passes through as it travels to reservoirs or aquifers. Additionally, chlorine-based disinfectants, like chlorine gas or sodium hypochlorite (bleach), used in water treatment can also contribute chloride ions to tap water.
Keep in mind that this explanation is based on the given information and qualitative analysis of the tap water. It is important to note that the actual composition of tap water may vary depending on location and specific water treatment processes employed in your area. Therefore, for a more accurate understanding, it's recommended to consult local water quality reports or contact the appropriate water authority.