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This is a common misconception. Chemical changes can be reversed. It happens all the time, and there's a large branch of physical chemistry devoted to it. The problem stems from some teachers trying to oversimplify when teaching the difference between physical and chemical changes. A chemical change is one which produces a new substance, and a physical change is one which does not. Common examples of physical changes are melting and boiling water, and common examples of chemical changes are rusting and burning. Unfortunately, people extrapolate from these limited examples and their own limited knowledge, to say that since melting and boiling water is easy to reverse, and they don't know how to reverse rusting and burning, that 'chemical changes can't be reversed and physical ones can'. It just isn't true.
When we convert iron to steel, rusty scrap iron is often included in the mixture, and one of the reactions taking place in the converter vessel is the reduction of rust to iron. Burning isn't simple to reverse, not least because the products are usually carbon dioxide and water vapour which escape into the air. However, when plants photosynthesise they take carbon dioxide and water and convert them to glucose and oxygen, and eventually most fuels derive from that glucose. Additionally, not all physical changes are easy to reverse. If you freeze water you can easily turn it liquid again, true, but if you freeze liquid iron you have to heat it to 1538 degrees C to remelt it - hardly easy!
Keely Schneider
Wiki User
∙ 15y agochemical reactions are reactions to add and lose electrons and breaking and forming bonds, they don't affect the nucleus, which is were the protons are. The number of protons is what determines which element something is Nuclear reactions can change the nucleus.
Wiki User
∙ 8y agoUltimately, a chemical reaction is chemical bonds being rearranged. Chemical bonds are arrangements of the electrons between atoms, and electrons do not affect the identity of an atom. The number of protons in the nucleus determines the identity of an atom, and the nucleus is not affected by chemical changes.
Wiki User
∙ 10y agoTrue
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What is mechanical change?
is a change that you cant see
Is a cooked rice is an example of physical change?
no cooked rice is not a physical change but is an example of chemical change as we cant obtain the raw rice after cooking it
How are physical and chemical changes different in two ways?
a physical change can be reversed but a chemical changes is not. you can all tell the different from a physical and chemical change by seeing if the color or if the substances is still in it normal element and it a chemical change if it has been change to a new substances like a burn paper change to Ashes. It is all most a physical change but it can not be reversed back.
How is a chemical change different from a physical change?
a physical change can be reversed a chemical one can'tA chemical change is when a new substance, with new and different properties, is produced. The identity of the original substance is changed. In contrast, a physical change is when one or more of a substance's physical properties have simply been altered; no new substance is produced.
What is a chemical and physical change?
Physical change - a change in a substance that does not involve a change in the identity, including a change in state between solid, liquid and gas phases.Chemical change - a change which one or more substances are converted into different substances, some indications are burning, rusting, color changes etc.physical change can be changedbut in chemical change chemicals are mixed togetherfor example if we are sick that is a physical changewe have to change healthy as wellwhen we mix salt in a dish,can we take out that again?neverthis is chemical changeA physical change is when the object undergoes a change that can be reversed, such as mixing water with salt, melting ice, or freezing or vaporizing water. A chemical change is a change that changes a substance into something else entirely, and therefore cannot be reversed. Examples would be mixing vinegar and baking soda or turning batter into bread.chemical change is when during a chemical reaction a new substance will be formed while in physical change no new substances are formed
Why cant a chemical reaction be put back the same?
cause chemical reactions cant be reversed
Is baked bread a chemical change?
Yes it is because the chemical properties change and it cannot be reversed.
How tyo recgonize chemical and physical change?
think if it can be reversed. if it is easially reversed, it is most likely physical. ie. if you bake a cake, you cant make it go back to a batter, so it is a chemical change. if you freeze an ice cube, you can just melt it and it goes back to water, so its a physical change.
What is a the difference between a chemical and physical change?
A physical change can be reversed such as an ice cube melting. A chemical change, on the other hand, cannot be reversed such as burning wood.
What are the differences between the physical and chemical?
in changes. Physical changes can be reversed. E.g. if you were to melt a block of ice, and then freeze it again, it would to some degree be reversed. This is a physical change. However, if you were to burn a peace of toast, the change would be chemical. Once the toast is burnt you cant get it back.
Is combustion a physical change?
NO its a chemical change for it can't be reversed
What type of change is an eyeshadow physical or chemical?
it is chemical because it can not be reversed
Is rusting a phsyical change?
Rusting is a chemical change because under it iron goes under oxidation and oxidation is a chemical process. Also, a physical change can be reversed but a chemical change cannot and rusting cannot be reversed. Hence also rusting is a chemical change.
Burning is what form of change?
it is a chemical change because it cannot be reversed
When a kettle is boiled you can tell it is NOT chemical change because?
the change is easily reversed so it is a physical change not a chemical change
Why is a firework an example of a chemical change in a fourth grade answer?
A chemical change can not be reversed. Obviously the fire work can not be put back together because it has reacted, not being able to be reversed, and therefore, being classified as a chemical change.
Explain what a chemical change is?
a chemical change is a change which brings about a change in the chemical properties of a substance which cannot be reversed through physical means like heating or cooling.
