Introduction:

When we burn a piece of wood, all that remains is a small pile of ashes. Where did the wood go? What property of wood caused this change? All the properties studied in the previous lesson and used in classification are easily observable physical properties. Furthermore, when these properties change, the original substance's composition remains constant. However, in the case of burning wood, something different happens. Some properties indicate a change in the original substance's composition. Chemical properties are the features that indicate a substance's tendency to undergo a change in its original composition due to a chemical reaction, resulting in new substances.

What do chemical properties indicate about a substance?

Article Outline:

1. Common Chemical Properties

2. Chemical Change

3. Common Reactions

4. Heat and Light

5. Evidence of Change

6. Conclusion

Common Chemical Properties:

It is not necessary to be in a laboratory to observe changes caused by chemical properties. These changes are called chemical changes.

Chemical Change:

It is a change that occurs in a substance's composition due to its chemical properties, resulting in the production of one or more new substances. For example, the fire burning in wood produces chemical changes. Oxygen in the air reacts with wood, causing it to burn and produce a new substance called ash. Wood is a combustible material, so this chemical property is called flammability or combustibility. Some materials have warnings to keep them away from heat and flames due to their flammability. Non-combustible materials, like stones, do not catch fire easily.

Common Reactions:

Chemical reactions occur between certain substances and atmospheric oxygen, forming the substance's oxide or element. For instance, iron reacts with atmospheric oxygen in the presence of water, forming iron oxide (rust). The iron gate, if not painted, rusts and corrodes over time. Additionally, components of some fruits, like bananas and apples, react with atmospheric oxygen, causing their color to turn brown when peeled and exposed to air. Elements also react with other elements, as shown in the middle image, where the silver vessel loses its silver luster due to the reaction of silver with substances in the air. The ability of substances to react with oxygen or sulfur, among others, is an example of a chemical property.

Heat and Light:

Both light and heat cause chemical changes in some substances. Vitamins are stored in dark brown bottles to prevent degradation due to light exposure. Limestone undergoes a chemical change when exposed to heat, producing carbon dioxide gas. Electricity can also induce chemical changes in some substances, breaking them down. Electrolysis of water, for example, yields hydrogen and oxygen, the components of water. Chemical changes differ from physical changes in that the former produce new substances with properties different from the original substances. Due to chemical changes, we enjoy various things in life; sugar, usually soft white crystals, turns into a new substance, caramel, when heated above a flame. Sugar also reacts with sulfuric acid, forming a new substance with completely different properties.

Evidence of Change:

How do you know that you have obtained a new substance? Is it just because it looks different? You can look for evidence to determine if a new substance has resulted from a chemical change. When baking a cake, gas bubbles form, and these bubbles are evidence of a chemical change. Upon closer inspection, you notice the holes left by the bubbles inside the cake. The chemical change caused by heat alters the taste and appearance of things, as observed when cooking food. Other evidence of chemical changes includes the production of heat, light, gas evolution, or changes in color, smell, or sound. Which of these clues can you hear or see when burning wood?

Can the substance be returned to its original state before the change?

You can determine whether the change is physical or chemical by knowing if you can reverse it through simple physical methods, returning the substance to its original state. If the change is physical, you can easily do so. For example, melted butter can be turned back into solid butter by placing it in the refrigerator, and after shaping playdough, it can be folded again to return it to the container. However, a chemical change cannot be reversed by physical methods. For example, ashes cannot be turned back into a piece of wood. Can you extract the egg from the cake? Can you also extract the white flour?

Which types of changes can be easily reversed?

Conclusion:

1. The study of a substance's chemical properties reveals that chemical changes indicate a fundamental transformation in the substance's composition, resulting in new substances with different properties from the original ones.

2. These changes reflect the remarkable ability of substances to transform and evolve. We can understand these changes through evidence that appears during chemical reactions, such as the production of heat, light, gas evolution, or changes in color, smell, or sound.

3. Inferring the occurrence of chemical changes opens up a deeper understanding of the world we live in, as these reactions happen everywhere around us, from the transformation of food during cooking to simple metal corrosion reactions.

4. Understanding the chemical properties of a substance remains one of the keys to uncovering the secrets of the world around us. Through research and experiments, we can build our knowledge and develop our understanding of how substances react and transform, contributing to the progress in various fields of life

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