Question

Balance each of the following equations that describe precipitation reactions. a. \(\mathrm{Na}_{2} \mathrm{SO}_{4}(a q)+\mathrm{CaCl}_{2}(a q) \rightarrow \mathrm{CaSO}_{4}(s)+\mathrm{NaCl}(a q)\) b. \(\operatorname{Co}\left(\mathrm{C}_{2} \mathrm{H}_{3} \mathrm{O}_{2}\right)_{2}(a q)+\mathrm{Na}_{2} \mathrm{S}(a q) \rightarrow\) \(\cos (s)+\mathrm{NaC}_{2} \mathrm{H}_{3} \mathrm{O}_{2}(a q)\) c. \(\mathrm{KOH}(a q)+\mathrm{NiCl}_{2}(a q) \rightarrow \mathrm{Ni}(\mathrm{OH})_{2}(s)+\mathrm{KCl}(a q)\)

Short answer

Short answers: a. Balanced equation: \(\mathrm{Na}_{2} \mathrm{SO}_{4}(a q)+\mathrm{CaCl}_{2}(a q) \rightarrow \mathrm{CaSO}_{4}(s)+2\mathrm{NaCl}(a q)\) b. Balanced equation: \(\operatorname{Co}\left(\mathrm{C}_{2} \mathrm{H}_{3} \mathrm{O}_{2}\right)_{2}(a q)+\mathrm{Na}_{2} \mathrm{S}(a q) \rightarrow \operatorname{CoS}(s)+2\mathrm{NaC}_{2} \mathrm{H}_{3} \mathrm{O}_{2}(a q)\) c. Balanced equation: \(2\mathrm{KOH}(a q)+\mathrm{NiCl}_{2}(a q) \rightarrow \mathrm{Ni}(\mathrm{OH})_{2}(s)+2\mathrm{KCl}(a q)\)

Step-by-step solution

Identify the elements

List the elements present in the equation: Na, S, O, Ca, and Cl.

Balance the atoms

We will balance the number of atoms of each element in the equation. - Na: There are 2 Na on the left side and 1 on the right side, so we need to put a coefficient of 2 in front of \(\mathrm{NaCl}\). - S: Already balanced (1 atom on both sides). - O: Already balanced (4 atoms on both sides). - Ca: Already balanced (1 atom on both sides). - Cl: Already balanced (2 atoms on both sides).

Rewrite the balanced equation

The balanced equation is: \(\mathrm{Na}_{2} \mathrm{SO}_{4}(a q)+\mathrm{CaCl}_{2}(a q) \rightarrow \mathrm{CaSO}_{4}(s)+2\mathrm{NaCl}(a q)\) b. Balancing the equation: \(\operatorname{Co}\left(\mathrm{C}_{2} \mathrm{H}_{3} \mathrm{O}_{2}\right)_{2}(a q)+\mathrm{Na}_{2} \mathrm{S}(a q) \rightarrow \cos (s)+\mathrm{NaC}_{2} \mathrm{H}_{3} \mathrm{O}_{2}(a q)\)

Identify the elements

List the elements present in the equation: Co, C, H, O, Na, and S.

Balance the atoms

We will balance the number of atoms of each element in the equation. - Co: There is 1 Co on the left side and an improper term (\(\cos (s)\)) on the right side. It should be written as \(\operatorname{CoS}(s)\). - C: There are 4 C on the left side and 2 on the right side, so we need to put a coefficient of 2 in front of \(\mathrm{NaC}_{2} \mathrm{H}_{3} \mathrm{O}_{2}\). - H: Already balanced (6 atoms on both sides). - O: Already balanced (4 atoms on both sides). - Na: Already balanced (2 atoms on both sides). - S: Already balanced (1 atom on both sides).

Rewrite the balanced equation

The balanced equation is: \(\operatorname{Co}\left(\mathrm{C}_{2} \mathrm{H}_{3} \mathrm{O}_{2}\right)_{2}(a q)+\mathrm{Na}_{2} \mathrm{S}(a q) \rightarrow \operatorname{CoS}(s)+2\mathrm{NaC}_{2} \mathrm{H}_{3} \mathrm{O}_{2}(a q)\) c. Balancing the equation: \(\mathrm{KOH}(a q)+\mathrm{NiCl}_{2}(a q) \rightarrow \mathrm{Ni}(\mathrm{OH})_{2}(s)+\mathrm{KCl}(a q)\)

Identify the elements

List the elements present in the equation: K, O, H, Ni, and Cl.

Balance the atoms

We will balance the number of atoms of each element in the equation. - K: There is 1 K on the left side and 1 on the right side, so it's already balanced. - O: There is 1 O on the left side and 2 on the right side, so we need to put a coefficient of 2 in front of \(\mathrm{KOH}\). - H: There are 2 H on the left side and 2 on the right side, so it's already balanced. - Ni: Already balanced (1 atom on both sides). - Cl: There are 2 Cl on the left side and 1 on the right side, so we need to put a coefficient of 2 in front of \(\mathrm{KCl}\).

Rewrite the balanced equation

The balanced equation is: \(2\mathrm{KOH}(a q)+\mathrm{NiCl}_{2}(a q) \rightarrow \mathrm{Ni}(\mathrm{OH})_{2}(s)+2\mathrm{KCl}(a q)\)

Key concepts

Precipitation Reactions

When two aqueous solutions are mixed, sometimes a solid forms and separates from the solution. This solid is known as a precipitate, and the reaction is called a precipitation reaction. In these reactions, ions in solution combine to form an insoluble product.
An example involves mixing solutions of sodium sulfate (\(\mathrm{Na}_{2}\mathrm{SO}_{4}\)) and calcium chloride (\(\mathrm{CaCl}_{2}\)). When these solutions are mixed, a white precipitate of calcium sulfate (\(\mathrm{CaSO}_{4}(s)\)) forms.
To identify precipitation reactions, it's crucial to recognize the reactants and predict the product. A solubility chart can help determine whether a compound will be insoluble in water and form a precipitate.

• The insoluble product in a precipitation reaction is called the precipitate.
• Solubility charts list compounds as soluble or insoluble to predict precipitates.

Properly balanced equations are vital in confirming the quantities of each substance involved.

Stoichiometry

Stoichiometry is the aspect of chemistry that deals with the quantitative relationships between the reactants and products in a chemical reaction. It's essential in solving chemical equations—or balancing them—so that the number of atoms for each element is conserved on both sides of the equation.
In a balanced chemical equation, coefficients are used to ensure equal numbers of each type of atom appear in the reactants and products.
For instance, the equation \(\mathrm{Na}_{2} \mathrm{SO}_{4}(a q)+\mathrm{CaCl}_{2}(a q) \rightarrow \mathrm{CaSO}_{4}(s)+2\mathrm{NaCl}(a q)\) is balanced, ensuring that we have the same number of sodium atoms, sulfate groups, calcium, and chloride ions on both sides of the equation.

• Each coefficient in a balanced equation represents the ratio of substances involved.
• Stoichiometry allows for the calculation of moles, masses, and volumes of reactants and products.
  

Mastering stoichiometry is key to predicting how much product will form from given reactants.

Chemical Reactions

Chemical reactions involve the reorganization of atoms in substances to form new products. These reactions often require breaking chemical bonds and forming new ones, which can be exothermic or endothermic depending on energy release or absorption.
There are different types of chemical reactions, including synthesis, decomposition, single replacement, and double replacement reactions. Precipitation reactions are a subset of double replacement reactions where two ionic compounds exchange partners to form new compounds, one of which is the insoluble precipitate.

• Reactants are the initial substances in a chemical reaction.
• Products are the new substances formed by the reaction.
• Energy is often involved in chemical reactions as bonds are broken and formed.

Balancing chemical equations ensures the law of conservation of mass is maintained.

Inorganic Chemistry

Inorganic chemistry is a branch of chemistry dealing with the properties and behavior of inorganic compounds. These usually consist of compounds that do not contain carbon-hydrogen bonds, such as metals, salts, and minerals.
Precipitation reactions, like the reactions mentioned in the exercises, are part of inorganic chemistry. Understanding these types of reactions helps explain how salts and minerals form naturally and the methods used to isolate metals from ores.

• Inorganic chemistry often involves studying materials not typically found in living organisms.
• It covers a wide array of compounds, including metals, salts, oxides, and nonmetals.
• Knowledge of inorganic chemistry is crucial in the development of new materials, catalysis, and industrial processes.

By mastering inorganic reactions, we can better understand processes like metal corrosion, water purification, and the creation of ceramics.