The Basics of Chemical Changes
Chemical changes are a fundamental part of chemistry. These changes occur when substances interact with each other, creating new substances with different properties. During this process, atoms and molecules are rearranged, and new bonds are formed. Chemical changes can be seen in everyday life, such as when food is cooked or when rust forms on metal.
What Doesn’t Change in a Substance?
While chemical changes involve the formation of new substances, there are some things that don’t change during this process. These include the number of atoms or molecules in a substance, as well as the total mass of the substance. This is known as the law of conservation of mass.
Examples of the Law of Conservation of Mass
The law of conservation of mass can be seen in many chemical reactions. For example, when baking soda and vinegar are mixed, they react to form carbon dioxide gas, water, and sodium acetate. While the appearance of the mixture changes, the total mass of the system remains the same. Another example is the combustion of propane gas. When propane reacts with oxygen to produce carbon dioxide and water, the total mass of the reactants is equal to the total mass of the products.
Other Properties that Don’t Change
In addition to mass, there are other properties that don’t change during a chemical change. These include the density, color, and temperature of the substance. While the appearance of the substance may change, these properties remain constant.
Why These Properties Don’t Change
The reason these properties don’t change is that they are not dependent on the chemical structure of the substance. Instead, they are determined by factors such as the arrangement of molecules and the amount of energy in the system. For example, the density of a substance is determined by the mass of its molecules and the volume they occupy. During a chemical change, the mass of the molecules may change, but the volume they occupy remains the same. Therefore, the density of the substance does not change. Similarly, the color of a substance is determined by the way it absorbs and reflects light. This property is determined by the arrangement of molecules in the substance, which does not change during a chemical change.
Conclusion
In conclusion, while chemical changes involve the formation of new substances, there are some properties that do not change during this process. These include the number of atoms or molecules in a substance, as well as the total mass, density, color, and temperature of the substance. Understanding these properties is essential for understanding chemical reactions and their impact on the world around us.