Question

Which will give white ppt. with \(\mathrm{AgNO}_{3}\) ?

Short answer

The compound that gives a white precipitate with silver nitrate (AgNO₃) is silver chloride (AgCl).

Step-by-step solution

Review solubility rules

Before we proceed to determine which compound would produce a white precipitate, let's first remind ourselves of the solubility rules for ionic compounds. Here are several relevant solubility rules: 1. Compounds containing the following ions are generally soluble: sodium (Na⁺), potassium (K⁺), ammonium (NH₄⁺), and nitrate (NO₃⁻). 2. All chlorides (Cl⁻), bromides (Br⁻), and iodides (I⁻) are soluble, except when combined with silver (Ag⁺), lead (Pb²⁺), and mercury (Hg₂²⁺). 3. Most sulfates (SO₄²⁻) are soluble, but those with lead (Pb²⁺), calcium (Ca²⁺), strontium (Sr²⁺), and barium (Ba²⁺) ions are not soluble.

List possible compounds

Now let's list some possible compounds that could react with AgNO₃ to produce white precipitates: 1. AgCl (silver chloride) 2. AgBr (silver bromide) 3. AgI (silver iodide) 4. Ag₂SO₄ (silver sulfate) 5. Ag₂CO₃ (silver carbonate)

Apply solubility rules

To find which compound would produce a white precipitate with AgNO₃, we need to apply the solubility rules mentioned earlier. Compounds with anions that form insoluble compounds with silver ions (Ag⁺) include chlorides, bromides, and iodides. Therefore, the possible compounds that would form a white precipitate are: 1. AgCl (silver chloride) 2. AgBr (silver bromide) 3. AgI (silver iodide)

Determine the white precipitate

While all three of the compounds listed in Step 3 would form precipitates, we need to determine which compound would specifically produce a white precipitate. Referring to the known colors of silver halides, we can conclude that: 1. AgCl is a white precipitate 2. AgBr is a pale yellow precipitate 3. AgI is a yellow precipitate

Answer

Based on the analysis and the solubility rules, the compound that gives a white precipitate with silver nitrate (AgNO₃) is silver chloride (AgCl).

Key concepts

AgNO3 Reactions

Silver nitrate (AgNO_3) is a versatile chemical in inorganic chemistry, often used in various reactions, especially for precipitation tests in qualitative analysis. When AgNO_3 reacts with halide ions like chloride (Cl^-), bromide (Br^-), or iodide (I^-), it forms corresponding silver halides, which can precipitate out of solution. For students learning about these reactions, it's crucial to remember that the solubility of the resulting compound dictates whether it will form a precipitate. For instance, when AgNO_3 is mixed with a sodium chloride (NaCl) solution, a white precipitate of silver chloride (AgCl) forms, which is insoluble in water.

To predict the outcome of reactions involving AgNO_3, it helps to keep in mind that silver nitrate is an ionic compound that dissociates completely in water to give silver (Ag^+) and nitrate (NO_3^-) ions. Any ionic compound formed by the combination of Ag^+ with an anion that's not generally soluble according to solubility rules will result in a precipitate. This concept applies not just to halides, but to other ion groups as well, such as carbonates or sulfides, which may also form precipitates under the right conditions.

Precipitation Reactions

Precipitation reactions are a fundamental part of inorganic chemistry that occur when two soluble salts react in aqueous solution to form at least one insoluble product, known as a precipitate. These reactions are easily identifiable as they produce a solid that separates from the liquid solution. The formation of a precipitate can often be predicted using solubility rules. In a classroom setting or homework exercise, understanding the solubility of different compounds helps students deduce the outcome of these reactions.

For example, when solutions containing Ag^+ ions and halide ions (Cl^-, Br^-, I^-) are combined, the respective silver halides form as solids. Students should be encouraged to write the net ionic equations for these precipitation reactions, which provide a more straightforward representation of the process by omitting the spectator ions. In essence, the essential learning point is that precipitation reactions involve the formation of a product that is insoluble in the reaction medium, leading to its separation as a distinct phase.

Silver Halides Solubility

Among the various compounds formed between silver ions (Ag^+) and halides (Cl^-, Br^-, I^-), silver halides have distinctive solubility characteristics that are important for students to grasp. Silver chloride (AgCl) is known for its white precipitate, silver bromide (AgBr) for a pale yellow one, and silver iodide (AgI) shows a more intense yellow coloration. These colors are indicative of their solubility, with AgCl being virtually insoluble in water, which is why it appears prominently as a white precipitate.

In a classroom practice, it would be beneficial for students to perform experiments to observe the formation of these silver halides upon mixing AgNO_3 with solutions of sodium chloride (NaCl), sodium bromide (NaBr), or sodium iodide (NaI). This hands-on experience solidifies their understanding of the solubility rules and provides a visual confirmation of theoretical predictions. It should be emphasized that while some silver compounds may have limited solubility, such as Ag_2SO_4 with slightly soluble sulfate ions, it is the silver halides' distinct lack of solubility that makes them particularly noteworthy in this context.