【PEP Edition】Grade 9 Chemistry (Upper): Fire Across Civilizations — The Mysteries and Applications of Combustion

From Prometheus's myth of stealing fire to the hydrogen-oxygen engines of modern space rockets,combustionis the most important chemical reaction in human history. It not only drove the evolution of tools but also serves as the core energy source sustaining modern society. Understanding the essence of combustion is the bridge from the macroscopic flame to the microscopic oxidation reaction.

Core Scientific Definition

Key Term: Combustion. In summary: Under normal conditions, a vigorous oxidation reaction between a combustible substance and oxygen that produces light and heat is called combustion.
Source of Energy: In today's world, most of the energy needed by humanity is produced through chemical reactions. From prehistoric wood to fossil fuels, the efficiency of energy conversion has determined the heights of civilization.
The Balance of Conditions: Combustion requires three conditions simultaneously: a combustible substance, oxygen, and a temperature reaching the ignition point. Mastering these conditions allows us both to harness energy and to extinguish fires effectively.

Civilization's Revelation

Combustion not only provides us with warmth and power, but also comes with resource consumption and environmental changes. We need to find a scientific balance between "energy acquisition" and "sustainable development," moving toward cleaner hydrogen energy and new energy sources.

QUESTION 1

According to the summary of the "Key Term," what is the essential definition of combustion under normal conditions?

A simple luminescent phenomenon

A vigorous oxidation reaction between a combustible substance and oxygen

A reaction that only occurs with heat absorption

Any light-and-heat-producing phenomenon that doesn't require oxygen

QUESTION 2

When you fan a coal stove, why does the flame grow stronger? But when you fan a candle flame, why does it go out?

The coal stove produces less carbon dioxide than the candle

Fanning the coal stove supplies more oxygen; fanning the candle removes heat, dropping the temperature below the ignition point

The candle has a higher ignition point than coal

Fanning the coal stove changes the ignition point of the coal

QUESTION 3

In today's society, what produces most of the energy needed by humanity?

Simple mechanical energy conversion

Nuclear fission reactions

Chemical reactions

Gravitational energy

QUESTION 4

[Reading context: Add 300 mL of hot water to a 500 mL beaker... introduce oxygen...] Why does white phosphorus, which does not burn in hot water, start burning after oxygen is introduced?

Oxygen lowers the ignition point of white phosphorus

The white phosphorus gets hotter in the water

It satisfies the condition of contact between white phosphorus and oxygen

QUESTION 5

[Reading context: When oil in a wok catches fire while cooking, you can put in a lot of vegetables...] What principle does this fire-extinguishing method use?

Oxygen isolation

Lowering the temperature below the ignition point

Removing the combustible material