explain five different characteristics of chemical changes with example
Answers
Explanation:
1.Shape can change the substance .
2.New substance is formed.
3. It is not reversible change.
4. It is a permanent change.
5.The properties of substance are not retain.
Example- Curd from milk.
Answer:
Five different characteristics of chemical changes are:
Changes in Temperature
While you can heat any substance, the spontaneous release of heat after mixing compounds together is a good indicator that a chemical reaction has taken place. Reactions that release heat are also called exothermic reactions. An example of a chemical change that releases heat is the thermite reaction, which is what causes fireworks to explode.
Changes in Color
A spontaneous color change is another a good clue that a chemical change has occurred. For example, products made of iron can develop rust, turning them from grey to reddish brown in color. This color change happens without human intervention as part of a chemical change called an oxidation reaction.
A Marked Odor
Any noticeable odor that occurs after a reaction begins (as opposed to the odors normally present for each compound) is a sign of a chemical reaction. For instance, a rotten egg gets its terrible smell from the irreversible decomposition reaction that occurs as it spoils.
Formation of a Precipitate
Sometimes when a chemical change occurs in a solution, a solid forms in that solution. This solid is a precipitate and is one of the most obvious ways to witness a chemical change since it can be very dramatic. A common household example is the appearance of soap scum, which is actually a precipitate that forms when minerals in hard water react with soap molecules.
Release of Bubbles
Bubbling that occurs during a reaction is an excellent sign that a chemical change is happening. Anyone who has made a volcano model erupt using vinegar and baking soda has seen this chemical change in action. The bubbles of carbon dioxide produced by mixing these common ingredients are actually the result of two reactions: an acid-base reaction followed by a decomposition reaction.
While telling the difference between a physical change and a chemical change can seem tricky at first, knowing the signs that indicate a chemical reaction has taken place can make this important scientific concept much more straightforward.