Question

For the following chemical reactions, determine the precipitate produced when the two reactants listed below are mixed together. Indicate “none” if no precipitate will form \(\mathrm{Sr}\left(\mathrm{NO}_{3}\right)_{2}(a q)+\mathrm{K}_{3} \mathrm{PO}_{4}(a q) \longrightarrow\)__________________(s) \(\mathrm{K}_{2} \mathrm{CO}_{3}(a q)+\mathrm{AgNO}_{3}(a q) \longrightarrow\)__________________(s) \(\mathrm{NaCl}(a q)+\mathrm{KNO}_{3}(a q) \longrightarrow\)__________________(s) \(\mathrm{KCl}(a q)+\mathrm{AgNO}_{3}(a q) \longrightarrow\)__________________(s) \(\mathrm{FeCl}_{3}(a q)+\mathrm{Pb}\left(\mathrm{NO}_{3}\right)_{2}(a q) \longrightarrow\)__________________(s)

Short answer

The precipitates formed in the given chemical reactions are as follows: 1. \(Sr_3(PO_4)_2 (s)\) 2. \(Ag_2CO_3 (s)\) 3. None 4. \(AgCl (s)\) 5. \(PbCl_2 (s)\)

Step-by-step solution

Familiarize yourself with solubility rules

To predict precipitation, we need to know the solubility rules. Some general solubility rules are: - Most nitrate (\(NO_3^-\)), acetate (\(CH_3COO^-\)), and perchlorate (\(ClO_4^-\)) salts are soluble. - Most alkali metal (group 1A) salts and ammonium \((NH_4^+)\) salts are soluble. - Most chloride, bromide, and iodide salts are soluble, except for those with silver (\(Ag^+\)), lead (\(Pb^{2+}\)), and mercury (\(Hg_2^{2+}\)) cations. - Most sulfate (\(SO_4^{2-}\)) salts are soluble, except for those with calcium (\(Ca^{2+}\)), strontium (\(Sr^{2+}\)), barium (\(Ba^{2+}\)), mercury (\(Hg_{2}^{2+}\)), and lead (\(Pb^{2+}\)) cations. - Most hydroxide salts are slightly soluble or insoluble, except those with alkali metals and calcium, which are soluble. - Most sulfide, carbonate (\(CO_3^{2-}\)), chromate (\(CrO_4^{2-}\)), and phosphate (\(PO_4^{3-}\)) salts are insoluble, except for those with alkali metals and ammonium.

Determine the possible products

Based on the reactants, determine the possible products by exchanging ions between various reactants. 1. \(Sr(NO_3)_2 (aq) + K_3PO_4 (aq) \longrightarrow Sr_3(PO_4)_2 (s) + 6KNO_3 (aq)\) 2. \(K_2CO_3 (aq) + AgNO_3 (aq) \longrightarrow 2Ag_2CO_3 (s) + 2KNO_3 (aq)\) 3. \(NaCl (aq) + KNO_3 (aq) \longrightarrow NaNO_3 (aq) + KCl (aq)\) 4. \(KCl (aq) + AgNO_3 (aq) \longrightarrow AgCl (s) + KNO_3 (aq)\) 5. \(FeCl_3 (aq) + Pb(NO_3)_2 (aq) \longrightarrow 3PbCl_2 (s) + 2Fe(NO_3)_3 (aq)\)

Predict the precipitates using solubility rules

Use solubility rules to determine which of the possible products will form a precipitate. 1. \(Sr(NO_3)_2 (aq) + K_3PO_4 (aq) \longrightarrow Sr_3(PO_4)_2 (s) + 6KNO_3 (aq)\) - Soluble: \(KNO_3\) - Insoluble: \(Sr_3(PO_4)_2\) - Precipitate: \(Sr_3(PO_4)_2\) 2. \(K_2CO_3 (aq) + AgNO_3 (aq) \longrightarrow 2Ag_2CO_3 (s) + 2KNO_3 (aq)\) - Soluble: \(KNO_3\) - Insoluble: \(Ag_2CO_3\) - Precipitate: \(Ag_2CO_3\) 3. \(NaCl (aq) + KNO_3 (aq) \longrightarrow NaNO_3 (aq) + KCl (aq)\) - Soluble: \(NaNO_3, KCl\) - No precipitate. 4. \(KCl (aq) + AgNO_3 (aq) \longrightarrow AgCl (s) + KNO_3 (aq)\) - Soluble: \(KNO_3\) - Insoluble: \(AgCl\) - Precipitate: \(AgCl\) 5. \(FeCl_3 (aq) + Pb(NO_3)_2 (aq) \longrightarrow 3PbCl_2 (s) + 2Fe(NO_3)_3 (aq)\) - Soluble: \(Fe(NO_3)_3\) - Insoluble: \(PbCl_2\) - Precipitate: \(PbCl_2\)

Key concepts

Precipitation Reactions

Precipitation reactions are a type of chemical reaction where two aqueous solutions are mixed, and an insoluble solid, known as the precipitate, forms. These reactions occur when the ions from the reactants combine to create a compound that is not soluble in water. For instance, when solutions of lead nitrate and potassium iodide are mixed, lead iodide, which is insoluble, forms as a yellow precipitate. This happens because the newly formed ions in the solution collide and bind to form a solid, separating from the liquid phase.
Understanding precipitation reactions is crucial, as they help predict the outcome of mixing different substances. They are also used in various applications, such as water treatment and qualitative analysis in laboratories. Always remember that not all combinations of ionic solutions will lead to a precipitate; that's where solubility rules come in handy!

Solubility in Aqueous Solutions

The concept of solubility in aqueous solutions explains how substances dissolve in water. Solubility is the maximum amount of a substance that can dissolve in a solvent at a given temperature, forming a homogeneous solution. Different compounds have varying solubilities, which is why the solubility rules are essential to predict the formation of a precipitate.
Key rules to remember:

• Most nitrates, acetates, and alkali metal salts are soluble.
• Chlorides, bromides, and iodides are generally soluble, except with lead, silver, and mercury ions.
• Sulfates are soluble, except when paired with ions like calcium, strontium, and barium.

This knowledge helps in discerning which products will remain in solution and which will precipitate out when reactions occur. Knowing the factors that affect solubility, like temperature and the presence of common ions, is also crucial for predicting outcomes in chemical experiments.

Chemical Reactions Prediction

Predicting chemical reactions involves understanding how reactants will interact and what products will form. In aqueous solutions, ion exchange between dissolved substances can lead to new compounds, some of which may be insoluble and form a precipitate.
The steps in predicting these reactions include:

• Identifying the ions present in the reactants.
• Exchanging the ions to form new compounds.
• Applying solubility rules to determine if any of the new compounds are insoluble.

For example, mixing sodium chloride and silver nitrate solutions leads to the formation of insoluble silver chloride, which can be predicted using the solubility rules. Additionally, it's important to balance chemical equations to maintain the law of conservation of mass. Mastery in predicting reactions is invaluable in planning experiments and industrial chemical processes, enabling chemists to ensure safety and efficiency.