Chemical Reactions Overview

Chemical reactions are fundamental to developing new materials such as spacesuits and passenger aircraft.
Engineers utilize knowledge of chemical reactions to produce materials that are:
  - Strong
  - Light
  - Capable of withstanding high temperatures
Key products of chemical reactions also include:
  - Fuels
  - Metals
  - Pharmaceuticals
Prevalence of Chemical Reactions:
  - Present in everyday phenomena:
    - Subtle changes (e.g., temperature changes in ice packs, fruit ripening)
    - Spectacular changes (e.g., reaction between sulfuric acid and icing sugar)
    - Slow reactions (e.g., rusting of a car)
    - Fast reactions (e.g., fireworks explosions)
  - Controlled environments (e.g., laboratories) vs. uncontrolled (e.g., bushfires)
Digestion:
- Food is constantly being digested, releasing energy and resources for cell growth and repair.
- The breakdown of food happens quickly.
Chemical Change Definition:
- A chemical reaction occurs when the bonds between reactants are broken, and new bonds are formed in the products.
- This can occur in one or multiple steps.
Chemical Reactions and the Law of Conservation of Mass:
- Atoms are rearranged during reactions; all atoms at the beginning are present at the end.
- Formulae and equations are used to summarize reactions.
Classification of Chemical Reactions:
  - Various types:
    - Synthesis
    - Decomposition
    - Single displacement
    - Double displacement

1. Why is it hazardous to add water to concentrated acid?
2. Which two gases react explosively to form water?
3. Why is metallic gold found in nature while other metals like aluminum occur only as compounds?
4. How are metals separated from their compounds?
5. What happens when an acid and a base are mixed, resulting in a product safe for consumption?
6. What methods can alter the rate of chemical reactions?

Common Chemical Reactions:
  - Familiar examples prompt analysis of chemical processes:
    - a. Figures 5.2 a-c show visual evidence of chemical reactions.
    - b. Discuss additional information beneficial for observations made in part a.
    - c. A test tube reaction where a metal displaces hydrogen from an acid creating dihydrogen gas - identify the type of chemical reaction.
    - d. In another test tube, a solid forms from two solutions in a precipitation reaction - identify the type of reaction.
    - e. Another test tube involves a reactive metal dissolving in a less reactive metal's solution, leading to the latter's physical change.
    - f. Describe additional observations during any chemical reaction.
Chemical Reactions in Living Organisms:
  - a. What chemical reaction occurs in green plants with sunlight involvement?
  - b. Identify the physiological process breaking food from large to small molecules for absorption.
  - c. What chemical reaction happens in animal cells to convert stored energy from food?

Chemical reactions occur when atom bonds are disrupted, leading to:
  - Formation of new bonds
  - New arrangement of atoms
  - Creation of at least one new substance
Example Reaction (Illustrated in Figure 5.3):
- Describe the bond alterations during the reaction between oxygen and hydrogen.