Problem 72 - Chemistry Matter and Change

Question

Write skeleton equations for these reactions. a. lithium \((s)+\operatorname{gold}(\text { III ) chloride }(a q) \rightarrow\) lithium chloride \((a q)+\operatorname{gold}(s)\) b. iron(s) \(+\operatorname{tin}(\mathrm{IV})\) nitrate ( aq) \(\rightarrow\) iron (III) nitrate \((a q)+\operatorname{tin}(s)\) c. nickel(II) chloride(s) \(+\) oxygen \((\mathrm{g}) \rightarrow\) nickel(II) oxide(s) + dichlorine pentoxide(g) d. lithium chromate(aq) \(+\) barium chloride \((a q) \rightarrow\) lithium chloride (aq) + barium chromate(s)

Step-by-Step Solution

Answer

a. \(Li(s) + AuCl_3(aq) \rightarrow LiCl(aq) + Au(s)\) b. \(Fe(s) + Sn(NO_3)_4(aq) \rightarrow Fe(NO_3)_3(aq) + Sn(s)\) c. \(NiCl_2(s) + O_2(g) \rightarrow NiO(s) + Cl_2O_5(g)\) d. \(Li_2CrO_4(aq) + BaCl_2(aq) \rightarrow LiCl(aq) + BaCrO_4(s)\)

Step 1: Identify reactants and products

For this reaction, the reactants are lithium (Li) and gold(III) chloride (AuCl₃), and the products are lithium chloride (LiCl) and gold (Au).

Step 2: Write the skeleton equation

The skeleton equation for this reaction is: \(Li(s) + AuCl_3(aq) \rightarrow LiCl(aq) + Au(s)\) b. Reaction between iron and tin(IV) nitrate

Step 1: Identify reactants and products

For this reaction, the reactants are iron (Fe) and tin(IV) nitrate (Sn(NO₃)₄), and the products are iron(III) nitrate (Fe(NO₃)₃) and tin (Sn).

Step 2: Write the skeleton equation

The skeleton equation for this reaction is: \(Fe(s) + Sn(NO_3)_4(aq) \rightarrow Fe(NO_3)_3(aq) + Sn(s)\) c. Reaction between nickel(II) chloride and oxygen

Step 1: Identify reactants and products

For this reaction, the reactants are nickel(II) chloride (NiCl₂) and oxygen (O₂), and the products are nickel(II) oxide (NiO) and dichlorine pentoxide (Cl₂O₅).

Step 2: Write the skeleton equation

The skeleton equation for this reaction is: \(NiCl_2(s) + O_2(g) \rightarrow NiO(s) + Cl_2O_5(g)\) d. Reaction between lithium chromate and barium chloride

Step 1: Identify reactants and products

For this reaction, the reactants are lithium chromate (Li₂CrO₄) and barium chloride (BaCl₂), and the products are lithium chloride (LiCl) and barium chromate (BaCrO₄).

Step 2: Write the skeleton equation

The skeleton equation for this reaction is: \(Li_2CrO_4(aq) + BaCl_2(aq) \rightarrow LiCl(aq) + BaCrO_4(s)\)

Key Concepts

Chemical Reactions

A chemical reaction is a process where substances, known as reactants, are transformed into different substances, termed products.
This transformation involves breaking chemical bonds in the reactants and forming new bonds in the products. Chemical reactions are represented by chemical equations, which illustrate the identity and quantity of each substance involved.

In our provided examples, several types of chemical reactions are demonstrated:

• A single replacement reaction, where one element replaces another in a compound, as seen in the reaction between lithium and gold(III) chloride.
• A double replacement reaction, where exchange of ions takes place between two compounds, as exhibited by the reaction between lithium chromate and barium chloride.

Understanding the nature and type of reaction involved aids in predicting the products and writing the correct chemical equation for any chemical process.

Reactants and Products

Reactants and products are fundamental components of a chemical equation.
They are substances that are involved in a chemical reaction.

* **Reactants** are the starting materials in a reaction. In an equation, they are typically shown on the left side of the arrow. These are the substances that undergo change.
* **Products** are the substances formed as a result of a chemical reaction. In a chemical equation, they are on the right side of the arrow. These substances are produced during the transformation process.

For example, in the skeleton equation for lithium reacting with gold(III) chloride:

• Reactants: Lithium ( Li ) and Gold(III) chloride ( AuCl_3 )
• Products: Lithium chloride ( LiCl ) and Gold ( Au )

This clear labeling helps us track the conversion of reactants to products and is key in understanding the reaction happening at a molecular level.

Chemical Equation Balancing

Chemical equation balancing is crucial for accurately representing a reaction. It ensures that the same number of each type of atom appears on both sides of the equation, adhering to the law of conservation of mass.
Balancing an equation can often be challenging, but follows a systematic approach:

**Steps to Balance an Equation:**

• Write the skeleton equation with the correct formulas for all reactants and products.
• Count the number of each type of atom on both sides.
• Add coefficients (numbers before compounds) to balance atoms across the reaction.
• Repeat these adjustments until all atom types are balanced.
• Ensure that the coefficients have the simplest whole number ratio.

Remember, only coefficients can be changed, not subscripts in chemical formulas, as altering subscripts changes the substances involved in the reaction. Balancing equations is fundamental in deriving meaningful chemical information from formulas and understanding the quantitative relationships in chemical reactions.