What are the characteristics of a chemical change

Chemical Change — Definition, Properties, Types & Examples

Chemical change definition

A chemical change is a reaction that alters the chemical composition of a pure substance. They occur when a pure substance becomes one or more different pure substances. There are several types of chemical changes.

Properties of chemical changes

Every chemical change involves a chemical reaction, which changes the chemical bonds of the original substance.

Chemical reactions create one new chemical substance or several new substances (the products) from one or more reactants.

The products of a chemical reaction have different chemical properties and usually different physical properties than the reactants.

You can help yourself if you learn to recognize all the characteristics of chemical change.

Observing only one reaction is not enough to know you have a chemical change and not a physical change.

Expect to see several characteristics from this list of seven signs of a chemical change.

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Types of chemical changes

We see many types of chemical change all around us, and even within our bodies.

Here are eight types of chemical reactions:

Chemical changes can occur quickly, as with combustion. Chemical changes can occur slowly, as with iron rusting into iron oxide, or your body growing from a baby to an adult.

Chemical change examples

Imagine that you receive an unwelcome note on a scrap of paper from a classmate. What can you do? Burn it, cut it up, fold it into a paper airplane?

You can do a lot of physical and chemical things to a sheet of paper.

Burning the unwanted paper is an example of a chemical change.

You cannot get back the original paper because you destroyed the paper itself. No matter what you try, you cannot recover the paper and the writing.

For example, an explosion is a combustion reaction that will produce heat, light, sound, gas, a change in color, and a temperature change.

When oxygen ( O 2 ) reacts with fuel, it chemically changes to carbon dioxide ( C O 2 ) and water ( H 2 O ) while releasing energy. That is a combustion reaction; it is a chemical change.

Chemical changes in biology are known as biochemical changes. Two examples of biochemical changes include fermentation and photosynthesis.

What does a chemical change produce?

The products from the chemical change will also have almost no chemical properties or physical properties in common with the reactants. That piece of paper was cellulose; now, it is ash (carbon and some other compounds). The paper (the reactant) will never return.

Iron is magnetic, while iron sulfide that results from the synthesis of iron and sulfur is not magnetic. All chemical changes are one-way changes. Old substances transform into new substances.

Physical Vs. Chemical Changes

Chemistry and physics are better understood when you know how to classify physical and chemical changes. If you alter the shape, size, or state of matter of some object, but still have the object itself (in some form), you have performed a physical change.

Changes in states of matter include four physical changes for the four states of matter (solids, liquids, gases, and plasmas).

Specific names for these changes apply to liquids and solids, solids and gases, gases and liquids, and gases and plasmas.

Here is a list of reactions that physically change the state of matter; each one has its opposite:

With all physical changes, you can get back the original substance. Some physical changes are harder to reverse than others, but all physical changes can be “undone.”

Is ice melting a chemical change?

Melting an ice cube may show a change in temperature, but that is only one of eight signals, which is not enough to say that melting is a chemical change.

When ice (solid water) physically changes into liquid water, it is still water ( H 2 O ).

Chemical Change Quiz

See how well you understand chemical changes by tackling these questions.

Chemistry is challenging material, but please try your best before you peek at the answers below.

What you learned:

After working your way through this lesson and video, you have learned:

What are chemical changes? Characteristics, indicators and examples

Technologies This constitutes a key term that determines the force of change that moves the evolution of processes, in which certain elements combine to give rise to new compounds. Before the variations observed in a system, it was used to resort to strict terms such as destruction and disappearance , but an irrefutable principle is that matter is not created, nor is it destroyed, it is transformed, And this means that when the absence of something is observed, this means that it became part of another compound.

Chemical changes involve the transformation of elements into new compounds, which despite being a combination of the original elements can present totally different properties. There are processes in which the transformation is reversible, that is, through mechanical manipulation we can separate and / or reverse the change to obtain the original elements (physical change), this is not the case of a chemical change, because the main Its characteristic is the irreversibility of the process, so the products obtained cannot be returned to their original elements.

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Chemical change reactions

Every chemical reaction leads to a change of chemical type in which the reactant substances become new products through the change of the molecular structure, and the union of their bonds.

The determining principle in chemical processes is dictated by the law of conservation of mass de Lavoisier, which determines that the total mass, in the processes of chemical changes, remains unchanged, which means that the amount of mass consumed in the reactants must be reflected in the products.

The characteristics of the products obtained from chemical changes depend on different factors:

Number of atoms: The number of atoms present in each compound greatly influences the final product, as it determines the number of bonds and their nature, as well as directly influencing the molecular structure of the new compound. Considering by way of example that the element carbon with 2 valence atoms is reacting with oxygen (which occurs in bivalent form), the result of this reaction will be carbon monoxide (CO) which is a toxic gas. On the other hand, if we consider the same scenario, but this time we have the element carbon with a valence of 4, the result of the reaction will be carbon dioxide (CO 2 ), which is a vital gas in processes such as photosynthesis and respiration.

Temperature: Many consider it the determining factor in the development of a reaction, since a certain amount of energy is required for the process to start. An increase in temperature translates into an increase in the speed of the reaction, regardless of whether it is exothermic or endothermic. This is because, as the temperature increases, the number of molecules with an energy equal to or greater than the activation energy increases, thereby increasing the number of effective collisions between atoms.

Attraction and repulsion force: It is a physical quantity, also known as electrical charge, that determines the forces that attract or repel compounds, considering their magnetic field. This determines the ability of matter to share photons.

Concentration: The concentration of the participating elements is a determining factor in the occurrence of a reaction, since the higher the concentration there is a greater probability of coalitions.

Characteristics of chemical changes

Indicators that a chemical change has occurred

In order to distinguish when we are in the presence of a chemical change, a series of factors that must be taken into consideration are listed below:

Examples

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Difference Between Physical Change and Chemical Change

Last updated on December 30, 2017 by Surbhi S

In our daily life, we encounter many changes in our surroundings, though we do not notice them, such as souring of milk, rusting of iron, stretching of a rubber band, bread becoming toast, melting of wax, liting of a match, etc. All these changes that take place around us are physical change or chemical change. Physical changes are the changes that change the physical traits of the substance, without making any change in their internal structure.

On the other hand, a chemical change is one that affects the internal structure of the substance, so as to form a new substance. So, take a read of the article to understand the difference between physical change and chemical change.

Content: Physical Change Vs Chemical Change

Comparison Chart

Definition of Physical Change

Physical change is a process in which the substance experiences change in its physical properties like shape, size, colour, volume, appearance, state (i.e. solid, liquid, gas), etc., that, without making any change in their molecular composition. These changes are volatile in; that can be reversed using simple physical methods.

The same element or compound exists prior, or after change, i.e. original characteristics of the object remain unchanged. For example, Melting of wax, boiling of water, dissolving sugar in water, chopping wood, crumpling of paper, etc.

Definition of Chemical Change

Chemical Change is defined as the process in which the atoms of one or more substances are rearranged or combined to form a new substance. When a substance undergoes chemical change, the chemical properties of the substance changes and it is transformed into a different substance with different chemical composition. Evolution of energy, the formation of bubbles, change in odour, change in temperature are some signs of chemical change.

Alternately, known as chemical reaction, wherein the substances involved are known as reactants, and the outcome of the reaction is called product. Energy change is one of the characteristics of a chemical change, because of the formation of the new product. Once the chemical change takes place, it cannot be reversed. For example, adding vinegar to baking soda, bleaching a stain, fermenting of grapes, etc.

Key Differences Between Physical Change and Chemical Change

The points given below discusses significant differences between physical change and chemical change

Example of both changes occuring simultaneously

Conclusion

To sum up, physical change is any change that only transforms the substance’s physical properties, but chemical change results in the change in the chemical structure of the substances involved.

Chemical Change: Definition, Characteristics, Importance

A chemical change is the transformation of one material into another, resulting in new materials with different properties and one or more new substances. When we burn paper, it turns into ash. From this ash, we cannot get paperback. This is because the burning of paper is a chemical change.

Various types of changes can be seen occurring in the environment regularly. Some occur naturally, while human activities cause others to meet their needs. These changes can be classified into two types: physical and chemical change. To learn more about chemical change, read the below article.

Define Chemical Change

Those changes in which new substances are formed are called chemical changes. During a chemical change, a substance changes its chemical composition (or change in chemical properties). Chemical reactions are another term for chemical changes. Substances are converted into entirely new substances during a chemical change. In most cases, the new substances cannot be returned to their original form. This means that most chemical changes are irreversible.

Characteristics of Chemical Changes

The easily observable features of changes that take place as a result of chemical reactions are known as characteristics of chemical changes.

Thus, the various characteristics of a chemical change are as follows:

Examples of Chemical Change

Some examples of chemical changes are as follows:

6. The reaction between baking soda and vinegar: When baking soda and vinegar are combined, bubbles of carbon dioxide gas, as well as other substances are formed. Because carbon dioxide is formed as one of the new substances as a result of the reaction between baking soda and vinegar, it is said to be a chemical change.

7. The reaction between copper sulphate solution and iron: When an iron nail is immersed in a blue copper sulphate solution, a chemical reaction occurs, resulting in a green iron sulphate solution and a brown copper deposit on the iron nail.

The reaction between copper sulphate \((\rm_4)\) solution and iron \((\rm)\) is a chemical change because it produces two new substances such as iron sulphate \((\rm_4)\) solution and copper \((\rm)\).

Importance of Chemical Changes

In our daily lives, various types of chemical changes occur. Some are natural, while others are artificial. The majority of them are extremely beneficial to us. Some examples are as follows:

What is Physical Change?

Physical changes are those in which no new substances are formed. The substances involved in a physical change do not change their identity. Some physical processes can easily return to their original form. Physical changes can thus be easily reversed. The changes in physical state, size and shape of a substance are physical changes.

Some common examples of physical changes are: Melting of ice (to form water); Freezing of water (to form ice); Boiling of water (to form steam); Condensation of steam (to form water); Making a solution; Glowing of an electric bulb; and Breaking of a glass tumbler.

Difference between Physical Change and Chemical Change

The main differences between physical and chemical changes are as follows:

Summary

Those changes in which new substances are formed are called chemical changes. During a chemical change, a substance changes its chemical composition. Physical changes are those in which no new substances are formed. The substances involved in a physical change do not change their identity. Chemical change results in the evolution of gas, change in colour and release or absorption of energy in the form of heat, light and sound.

Q.1. What are \(5\) examples of a chemical change?
Ans: The five examples of chemical changes are rusting of iron, combustion, photosynthesis, ripening of fruits and curdling of milk.

Q.2. What is chemical change give example?
Ans: Those changes in which new substances are formed are called chemical changes. For example, burning of paper, cooking of food, burning of crackers, etc, are some examples of chemical change.

Q.3. What is a chemical change and a physical change?
Ans: The change in which no new substances are formed is called a physical change. The change in which new substances are formed is called a chemical change.

Q.4. What are \(3\) types of chemical changes?
Ans: The three types of chemical changes are Combination, decomposition and displacement reactions.

Q.5. Is chemical change reversible?
Ans: No, a chemical change is irreversible.

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Chemical Change Definition in Chemistry

What a Chemical Change Is and How to Recognize It

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A chemical change, also known as a chemical reaction, is a process in which one or more substances are altered into one or more new and different substances. In other words, a chemical change is a chemical reaction involving the rearrangement of atoms.

While a physical change can often be reversed, a chemical change typically cannot be, except through more chemical reactions. When a chemical change occurs, there is also a change in the energy of the system. A chemical change that gives off heat is called an exothermic reaction. One that absorbs heat is called an endothermic reaction.

Key Takeaways: Chemical Change

Examples of Chemical Changes

Any chemical reaction is an example of a chemical change. Examples include:

In comparison, any change that does not form new products is a physical change rather than a chemical change. Examples include breaking a glass, cracking open an egg, and mixing sand and water.

How to Recognize a Chemical Change

Chemical changes may be identified by:

It’s important to know that chemical change may occur without any of these indicators being obvious to the casual observer. For example, the rusting of iron produces heat and a color change, but it takes a long time for the change to be evident, even though the process is ongoing.

Types of Chemical Changes

Chemists recognize three categories of chemical changes: inorganic chemical changes, organic chemical changes, and biochemical change.

Inorganic chemical changes are chemical reactions that don’t generally involve the element carbon. Examples of inorganic changes including mixing acids and bases, oxidation (including combustion), and redox reactions.

Organic chemical changes are those that involve organic compounds (containing carbon and hydrogen). Examples include crude oil cracking, polymerization, methylation, and halogenation.

Biochemical changes are organic chemical changes that occur in living organisms. These reactions are controlled by enzymes and hormones. Examples of biochemical changes include fermentation, the Krebs cycle, nitrogen fixation, photosynthesis, and digestion.