Predict the products and write a net ionic equation for each of the following reactions. If no reaction occurs, write "no reaction." $$ \begin{array}{l}{\text { a. } \mathrm{K}_{2} \mathrm{CO}_{3}(a q)+\mathrm{CaCl}_{2}(a q) \longrightarrow} \\ {\text { b. } \mathrm{Na}_{2} \mathrm{SO}_{4}(a q)+\mathrm{AgNO}_{3}(a q) \rightarrow} \\ {\text { c. } \mathrm{NH}_{4} \mathrm{Cl}(a q)+\mathrm{AgNO}_{3}(a q) \rightarrow} \\\ {\text { d. } \mathrm{Pb}(s)+\mathrm{ZnCl}_{2}(a q) \rightarrow}\end{array} $$

Chemical reactions are processes where reactants transform into products. During a reaction, the bonds between atoms in the reactants are broken, and new bonds are formed to make the products. For students tackling chemical reactions, it’s crucial to identify the reactants and possible products, understand the role of valence electrons in bond formation, and learn to balance chemical equations to comply with the law of conservation of mass.

Key Steps in Chemical Reactions

• Identify the reactants presented in the exercise.
• Determine the possible products using knowledge of common reaction types (such as synthesis, decomposition, single replacement, double replacement, and combustion).
• Bond breaking and formation during the reaction can alter the chemical properties, which should be taken into account.
• Balance the equation to ensure that the same number of each type of atom appears on both the reactants and products side.

In the given exercise, balancing chemical reactions was the first step, ensuring that each side of the equation had equal numbers of atoms for each element.

Product prediction is a key skill in chemistry, allowing you to anticipate what substances will be formed in a chemical reaction. Familiarity with common reaction patterns, such as exchange reactions or neutralization, can guide predictions. For double displacement reactions, like the ones provided in the exercise, products are formed by exchanging ions between two compounds. To predict products:

• Look at the reactants’ ionic components and consider how they might be rearranged.
• Use knowledge of common ionic compounds to predict which combinations are most likely to occur.
• Consider the physical state of the products, which can depend on factors like solubility.

For example, when potassium carbonate reacts with calcium chloride, a double displacement reaction is expected, resulting in the formation of potassium chloride and calcium carbonate, as seen in the provided solution.

Solubility rules help determine whether a product will be soluble or insoluble in water, aiding in the prediction of reaction outcomes. A soluble substance will dissolve in water, forming an aqueous solution, while an insoluble substance will not dissolve and may form a solid precipitate. Here are the common rules:

General Solubility Rules

• Most nitrate (NO3-) salts are soluble.
• Alkali metal (group 1 elements) salts and ammonium (NH4+) salts are generally soluble.
• Chlorides (Cl-), bromides (Br-), and iodides (I-) are soluble, except when paired with silver, lead, or mercury.
• Most sulfate (SO42-) salts are soluble, with exceptions like barium sulfate, lead sulfate, and calcium sulfate.
• Most carbonate (CO32-), phosphate (PO43-), chromate (CrO42-), and sulfide (S2-) compounds are insoluble, with some exceptions for certain alkali metals and ammonium.

In the exercise solutions, these rules were crucial. For instance, calcium carbonate is insoluble, so upon mixing with soluble potassium carbonate and calcium chloride, it precipitates out of the solution, forming a solid as indicated by '(s)' in the chemical equations. The net ionic equations provide a clearer picture of the actual chemical change, showing only the ions involved in forming the product.