Problem 97 - Chemistry Matter and Change

Question

Complete the following chemical equation. $$\mathrm{CuCl}_{2}(\mathrm{s})+\mathrm{Na}_{2} \mathrm{SO}_{4}(\mathrm{aq}) \rightarrow$$

Step-by-Step Solution

Answer

\(\mathrm{CuCl}_{2}(\mathrm{s})+\mathrm{Na}_{2} \mathrm{SO}_{4}(\mathrm{aq}) \rightarrow \mathrm{CuSO}_{4}(\mathrm{aq})+2\mathrm{NaCl}(\mathrm{aq})\)

Step 1: 1. Identify the positive and negative ions in the reactants

For CuCl2, the positive ion is the copper ion (Cu2+) and the negative ion is the chloride ion (Cl-). For Na2SO4, the positive ion is the sodium ion (Na+) and the negative ion is the sulfate ion (SO4 2-).

Step 2: 2. Swap the positive ions in the reactants

According to the double displacement reactions, the positive ions in the reactants exchange places. The copper ion (Cu2+) will form a new compound with the sulfate ion (SO4 2-), and the sodium ion (Na+) will form a new compound with the chloride ion (Cl-).

Step 3: 3. Write the formulas of the new compounds formed

Copper(II) will combine with sulfate to form copper(II) sulfate, which has a formula of CuSO4. Sodium will combine with chloride to form sodium chloride, which has a formula of NaCl.

Step 4: 4. Balance the chemical equation

To balance the chemical equation, we need to make sure the number of atoms for each element is equal on both sides. The balanced equation is: \(\mathrm{CuCl}_{2}(\mathrm{s})+\mathrm{Na}_{2} \mathrm{SO}_{4}(\mathrm{aq}) \rightarrow \mathrm{CuSO}_{4}(\mathrm{aq})+2\mathrm{NaCl}(\mathrm{aq})\) The final balanced chemical equation is: \[\mathrm{CuCl}_{2}(\mathrm{s})+\mathrm{Na}_{2} \mathrm{SO}_{4}(\mathrm{aq}) \rightarrow \mathrm{CuSO}_{4}(\mathrm{aq})+2\mathrm{NaCl}(\mathrm{aq})\]

Key Concepts

Double Displacement Reaction

A double displacement reaction is a type of chemical reaction where two compounds react, and the positive ions (cations) and negative ions (anions) of the reactants swap places. This process often forms two new compounds. In the example of the reaction between copper(II) chloride (\(\mathrm{CuCl}_2\)) and sodium sulfate (\(\mathrm{Na}_2\mathrm{SO}_4\)), the copper ion \((\mathrm{Cu}^{2+})\) and the sodium ion \((\mathrm{Na}^+)\) exchange their partners. As a result, new compounds, namely copper(II) sulfate \((\mathrm{CuSO_4})\) and sodium chloride \((\mathrm{NaCl})\), are formed. This type of reaction is also known as a "metathesis reaction."
The key characteristics of a double displacement reaction include:

• Formation of two new compounds.
• Exchange of ions between the reactants.
• Often results in the formation of a precipitate, water, or a gas.

Recognizing these patterns helps to predict the products of reactions involving ion exchange.

Ion Exchange

Ion exchange is an essential concept in chemistry. It involves the swapping of ions between reactants during a chemical reaction. In the context of a double displacement reaction, ion exchange happens as positive ions, or cations, swap their corresponding negative ions, or anions, between two reactant compounds.
In the given reaction between \(\mathrm{CuCl}_2\) and \(\mathrm{Na}_2\mathrm{SO}_4\), the ion exchange process can be understood as follows:

• Copper ions \((\mathrm{Cu}^{2+})\) pair with sulfate ions \((\mathrm{SO_4}^{2-})\).
• Sodium ions \((\mathrm{Na}^+)\) pair with chloride ions \((\mathrm{Cl}^-)\).

This exchange of partners results in two new compounds forming: \(\mathrm{CuSO_4}\) and \(\mathrm{NaCl}\). The ion exchange mechanism is crucial for the understanding of numerous chemical processes, including water purification and various synthetic reactions.

Compound Formation

Compound formation refers to the process by which two or more elements or ions combine to form a compound with new properties. In chemical reactions, the reorganization of atoms leads to the creation of new substances. When copper(II) chloride \((\mathrm{CuCl_2})\) reacts with sodium sulfate \((\mathrm{Na}_2\mathrm{SO}_4})\), compound formation occurs through the exchange and bonding of ions.
In our example, as the ions swap partners:

• Copper \((\mathrm{Cu}^{2+})\) combines with sulfate \((\mathrm{SO_4}^{2-})\) to form copper(II) sulfate \((\mathrm{CuSO_4})\).
• Sodium \((\mathrm{Na}^+)\) combines with chloride \((\mathrm{Cl}^-)\) to form sodium chloride \((\mathrm{NaCl})\).

The resulting compounds display properties distinct from their original reacting substances. Understanding compound formation helps in identifying how different elements interact and bond, providing a foundation for studying further chemical reactions and processes.

Chemical Reaction

A chemical reaction occurs when substances undergo a transformation producing one or more different substances. This transformation involves breaking old bonds and forming new ones. In the reaction between copper(II) chloride \((\mathrm{CuCl_2})\) and sodium sulfate \((\mathrm{Na}_2\mathrm{SO}_4})\), a chemical reaction takes place where the reactants interact to create copper(II) sulfate \((\mathrm{CuSO_4})\) and sodium chloride \((\mathrm{NaCl})\).
Key steps in a chemical reaction include:

• Identification of reactants and their respective ions.
• Exchange of ions through processes like double displacement.
• Formation of new compounds with distinct chemical formulas.
• Balancing the equation to satisfy the law of conservation of mass.

In the balanced equation \(\mathrm{CuCl}_{2} + \mathrm{Na}_{2} \mathrm{SO}_{4} \rightarrow \mathrm{CuSO}_{4} + 2\mathrm{NaCl}\), the number of atoms for each element is equal on both sides, maintaining the principle of matter conservation. Understanding chemical reactions is crucial for various applications, from scientific research to industrial production and everyday life.