which of the following demonstrates a chemical change
See your other post above. Note that copy and paste doesn't work on this site.
Well, I'm not a scientist, but I can give you a clownish answer! How about this: If your sandwich suddenly turns into a rock-hard piece of charcoal, that's definitely a chemical change! Your taste buds will be like, "Whoa, what happened to my tasty lunch?!"
A chemical change is a process in which one or more substances are converted into new substances with different chemical properties. Here are a few examples of chemical changes:
1. Rusting of iron: When iron reacts with oxygen in the presence of moisture, it forms iron oxide, commonly known as rust. This chemical reaction is a clear example of a chemical change.
2. Combustion: When a substance, such as wood or gasoline, burns, it undergoes a chemical reaction with oxygen in the air to produce carbon dioxide, water, and heat. This is also a chemical change.
3. Digestion: When you eat food, it goes through a series of chemical changes in your body to break down complex molecules into simpler ones. This involves the action of various enzymes, acids, and other chemicals in your digestive system.
4. Photosynthesis: This is the process by which plants convert sunlight, carbon dioxide, and water into glucose and oxygen. It involves a series of complex chemical reactions that result in the production of new substances.
These examples demonstrate chemical changes as they involve the formation of new substances with different chemical properties.
A chemical change can be defined as a process in which one or more substances are converted into new substances with different physical and chemical properties.
Here are a few examples that demonstrate a chemical change:
1. Rusting: When iron comes into contact with oxygen and water, it undergoes a chemical reaction known as oxidation. The iron reacts with oxygen to form iron oxide, which is commonly known as rust. This change is irreversible and represents a chemical transformation.
2. Combustion: When a fuel (such as wood, paper, or gasoline) undergoes a reaction with oxygen in the presence of heat, it leads to combustion. This chemical reaction releases energy in the form of heat and light, resulting in the formation of new products such as carbon dioxide and water vapor.
3. Fermentation: Fermentation is a chemical process in which sugars are converted into alcohol or organic acids by the action of enzymes produced by microorganisms, such as yeast. This process is important in bread baking, brewing, and winemaking.
To determine if a change is a chemical change, you can look for indicators such as the formation of new substances, changes in color, production of gas, temperature changes, or the release or absorption of energy. It is important to note that physical changes (such as changes in state or shape) can be reversed, while chemical changes cannot be easily undone.