Question

Describe how you would explain to someone how a chemical reaction changes one set of compounds into another.

Short answer

To explain how a chemical reaction changes one set of compounds into another, I would introduce the concept of a chemical reaction as a process in which reactants are transformed into products due to the rearrangement of atoms. I would then discuss the law of conservation of mass, which states that the total mass of reactants is equal to the total mass of products. Using the example of hydrogen gas and oxygen gas reacting to form water, I would explain how atoms from the reactants break their bonds and rearrange to form new bonds, resulting in the formation of the product. It's important to ensure that the chemical equation is balanced to uphold the conservation of mass.

Step-by-step solution

Introducing chemical reactions

A chemical reaction is a process in which one or more substances, called reactants, are transformed into one or more different substances, known as products. Chemical reactions occur due to the rearrangement of atoms that form new bonds, ultimately changing the properties of the original substances.

Understanding reactants and products

In a chemical reaction, reactants are the substances that undergo change, and products are the resulting substances formed after the reaction. Reactants and products can be elements or compounds, and they are represented using chemical formulas. It's essential to understand that during a chemical reaction, the atoms that were present in the reactants are still present in the products - only the arrangement of these atoms changes.

Conservation of mass in chemical reactions

The law of conservation of mass states that the total mass of the reactants is equal to the total mass of the products in a chemical reaction. This means that no atoms are created or destroyed during a chemical reaction - they are merely rearranged. It's important to ensure that the chemical equation representing the reaction is balanced, meaning that the number of atoms of each element on the reactant side is equal to the number of atoms of the same element on the product side.

Using a simple chemical reaction as an example

Let's consider a simple chemical reaction between hydrogen gas (H₂) and oxygen gas (O₂) to form water (H₂O). This reaction can be represented by the chemical equation: \(2H₂ + O₂ → 2H₂O\). In this reaction, the reactants are hydrogen gas and oxygen gas, and the product is water. Notice that the number of atoms for each element (hydrogen and oxygen) is the same on both sides of the equation, ensuring that the conservation of mass is upheld.

Explaining the rearrangement of atoms in a chemical reaction

During the hydrogen and oxygen reaction, the hydrogen and oxygen molecules break their bonds and rearrange themselves to form new bonds, producing water molecules. Each hydrogen molecule consists of two hydrogen atoms, and each oxygen molecule consists of two oxygen atoms. When the reactants collide with enough energy, their bonds break, allowing new bonds to form between the hydrogen and oxygen atoms. In this case, two water molecules are formed, each consisting of two hydrogen atoms bonded to one oxygen atom, resulting in the formation of the new product.

Key concepts

Reactants and Products

Understanding the concept of reactants and products is fundamental to grasping how chemical reactions work. In a chemical reaction, *reactants* are the substances you start with. They are the ones undergoing change due to the reaction. On the other hand, *products* are the new substances formed as the result of the reaction.
Think of reactants as ingredients and products as the dish you create.

• Reactants can include elements or compounds.
• Products are often compounds formed by the reactants.
• Both reactants and products are represented by chemical formulas.

During any chemical reaction, the atoms in the reactants are simply rearranged to form the products. This means, the atoms themselves remain unchanged; it is their arrangement that shifts, leading to the formation of completely new materials with potentially very different properties from the original reactants.

Conservation of Mass

The **law of conservation of mass** is a bedrock principle in chemical reactions. This law states that matter cannot be created or destroyed in a chemical reaction. Therefore, the mass of the products must equal the mass of the reactants.
Every time there is a chemical reaction, the same number of each type of atom is maintained from start to finish.

• The number of atoms of each element in the reactants is equal to the number in the products.
• This equality is due to the fact that atoms are simply rearranged, not lost or gained.
• The mass is conserved even if the elements form new compounds.

Consider the reaction of hydrogen and oxygen to form water. No hydrogen or oxygen atoms disappear; they just form a new, combined product.

Balancing Chemical Equations

**Balancing chemical equations** ensures that the principle of the conservation of mass is respected. It involves making sure that you have the same number of each type of atom on both sides of the reaction's equation.

• Start by counting the atoms of each element within the reactants and products.
• If the numbers on each side aren't equal, multiply the quantities by suitable coefficients until they balance.
• The smallest set of whole numbers should be used to balance the equation.

For instance, when balancing the reaction between hydrogen and oxygen to form water, the equation starts as \(H_2 + O_2 → H_2O\). To balance, adjust it to \(2H_2 + O_2 → 2H_2O\), ensuring an equal number of hydrogen and oxygen atoms on each side. This balance mirrors the law of conservation of mass, maintaining equilibrium between reactants and products.