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new substances are formed with new properties.
when a object changes its form
A chemical reaction has occurred when the chemical identity of a the reactants is different from that of the products. The evidence for this could be obvious or very subtle. For instance, if a colorless gas reacts to form another colorless gas, there would be no visible sign of the reaction. However, often a chemical reaction will cause a change in color or the formation of a solid. The tools you might use to determine if a reaction has taken place depends a great deal on what the suspected reaction is (or what the products formed would be). The most common method is to use analytical chemical technique to verify the presence of the product molecules, or the disappearance of reactant molecules.
Note that there are many physical changes that can be confused with chemical changes. For instance, boiling water or freezing water results in many changes in the properties of water, but those are physical changes, not chemical ones. But whether water is liquid, solid or a gas, it is still water, and that is why it is a physical rather than chemical change.
See the Related Questions for more information about the difference between chemical and physical changes.
(Emperor-A) Here are some evidence they are-
A colour change
A gas given off
A temperature change
there are 7 ways to spot if a chemical reactions is occurring:
1. A Temperature change
2. A color change.
3. A precipitate is formed (an insoluble substance)
4. A gas is given off.
5. Light may be given off
6. Odor may be given off
7. Sound may be given off
Basically if there are any permanent changes to the object, such as burning, it can be considered a chemical reaction.
Also when there is bubbling or fizzing.
- A new substance may be created
- A change or peak in energy occurs.
- change in appearance of substance(s)
- Temperature change
- Precipitate
- Color change
You can tell when a chemical reaction occurs when there are changes in properties, a color change, and when the changes in properties precipitate.
The color change, Fomation of a precipitate, Formation of gas, and Temperature change
Evolution of a gas
heat/ energy
precipitate forms
color change
evolution of light
You could know by the color change, temperature change, a new substance may be created, etc..
First it changes into a complete different substance
Second it changes energy
Third it may change color
Fourth a solid may appear when two solutions are mixed together
Fifth is a gas might be produced from solids or liquids.
the smell and size.
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The following observations can help you to determine whether a chemical reaction has occurred:
- change of odour (smell)
- change of colour
- change in temperature, e.g. the production or loss of heat.
- change of form, e.g. burning paper
- light, heat, or sound is given off.
- formation of gases, often appearing as bubbles.
- formation of a precipitate (insoluble particles that usually sink to the bottom)
- the decomposition of organic matter, e.g. food rotting
- evident apparition of a new substance with a new chemical formula
There are quite a few indicators that a chemical change may have occurred. These include;- Change in color or luster. The release of gas or vapor. (noticeable odor or formation of bubbles) Change in temperature. (either cooling down or heating up) Formation of a precipitate. The release of heat and/or light & sound. A change in volume. The melting point or boiling point changes. A change in electrical conductivity occurs. A change in any distinctive chemical or physical properties occurs. Not all of these changes are necessarily proof of a chemical change, but they are a good indication and a starting point for further investigation. e.g. ruling out physical changes.
What else can I help you with?
What tells the story of a chemical reaction?
The balanced chemical equation for a reaction tells the story of a chemical reaction by showing the reactants that are consumed and the products that are formed. It also provides information on the stoichiometry of the reaction, including the ratios of reactants and products involved.
What is the fastest chemical reaction?
My Chemistry lecturer tells me that the combustion of Hydrogen and Oxygen into water is the fastest chemical reaction.
In a chemical reaction what tells you how many atoms or molecules of a reactant or a product take part in a reaction?
A subscript
What tells reactants products physical state and proportions of each substance in a chemical reaction?
A chemical equation
In a chemical reaction the left side of the equation which tells you what goes into the reaction are called the?
Products. Products ----> Reactants.
What do the formula of a chemical equation tell you?
The formula of a chemical equation tells you the type and number of atoms or molecules involved in a chemical reaction. It helps to balance the equation to ensure that mass is conserved and the reaction follows the law of conservation of mass.
What information does the coefficient provide in a chemical reaction?
It tells you the number of molecules or number of moles of each substance.
What is the purpose of writing a word equation in chemistry?
It is one way of representing a chemical reaction: it tells you what reacts and what is produced. Word equations are an efficient way to describe chemical changes, to help chemists recognize patterns, and to predict the products of a chemical reaction.
What does the law of conservation of mass tell about the mass of a reactants and products in a reaction before a chemical reaction and the ass of the products of the mass of products after a chemical?
The law of conservation of mass states that mass is neither created nor destroyed in a chemical reaction. This means that the total mass of the reactants before a chemical reaction is equal to the total mass of the products after the reaction. In other words, the mass of the reactants is the same as the mass of the products in a chemical reaction.
What does a word equation or a chemical reaction tell you?
I think that a chemical equation tells a chemist that substances you start with and substances you end with
What is the reactant of 10.0 grams of total mass What is the chemical reaction?
It is possible to have ten grams of anything. Specifying the total weight tells you nothing about which reactant you have or what reaction it will undergo.
What do the subscript and coefficent in a chemical equation tell us?
The subscript in a chemical equation tells us the ratio of atoms of each element present in a compound. The coefficient tells us the number of molecules or formula units involved in the reaction.
