Physical and Chemical Changes

The physical change of the substance does not change the content of the substance. In chemical reactions occurring in chemical reactions, new substances are formed and energy is released or absorbed

For example, even if one piece of paper is cut into small pieces, it is still paper. This is a physical change in paper shape and size. When the same piece of paper is burned, it breaks down into various substances that are not paper.

Physical changes can be reversed, chemical changes can not be undone, there is no special means to restore the material, if any. For example, a glass of water can be frozen while cooling and then heated to return to liquid form.

If people decide to mix sugar with water to make sugar water, this is a physical change as water is eliminated to evaporate and sugar crystals remain. But when people make cake recipes and use flour, water, sugar and other materials to bake them together, an extraordinary method is needed to separate the materials into their original shape .

If heat is released during a chemical change or reaction, it is called an exothermic reaction. When heat is absorbed by chemical changes and reactions, it is called endothermic reaction. The rate at which the chemical reaction takes place depends on the temperature and pressure and the concentration of the substance involved in the chemical reaction. Substances, sometimes called catalysts, are used to promote or encourage chemical reactions. Light useful for film processing

There are two types of material change: physical change and chemical change. As its name implies, physical changes affect the physical properties of substances and chemical changes affect the chemical nature of the substance. Many physical changes are reversible (such as heating and cooling), but chemical changes are usually irreversible, or can be reversed only by additional chemical changes. Another way of thinking is that substances are not fundamentally different substances due to physical changes, but substances may become chemically new substances due to chemical changes. For example, there are two physical changes in a mixed smoothie. To change the shape of each fruit and to mix various fruits. During the mixing process, there is no change in the chemical substances in the smoothie ingredients (for example, vitamins in water and water do not change), so it can be seen that there is no chemical change.

All substances have different physical and chemical properties and may undergo physical or chemical changes. Physical properties such as hardness and boiling point, and physical changes such as melting and freezing do not include changes in the composition of the substance. Chemical properties such as flammability and acidity and chemical changes such as rust involve the generation of substances different from existing materials. Measurable attributes fall into two categories. The wide nature depends on the amount of material present, such as the quality of gold. Reinforcement does not depend on the amount of material present, such as the density of gold. Heat is an example of wide nature, temperature is an example of intensive nature.