how are chemical changes different from physical changes
they involve heat
they are reversible
they form new substances
or they include shifts in the phase of matter
Chemical changes are different from physical changes in several ways:
1. Formation of new substances: Chemical changes result in the formation of new substances with different chemical properties. Bonds between atoms are broken and new bonds are formed, leading to the creation of entirely different compounds or elements. In contrast, physical changes do not lead to the formation of new substances.
2. Irreversibility: Chemical changes are typically irreversible, meaning it is difficult or impossible to reverse the reaction and retrieve the original substances. Once the reaction occurs and new compounds are formed, it is challenging to revert back to the starting materials. On the other hand, physical changes are often reversible, allowing the substances to return to their original state with no change in chemical properties.
3. Energy changes: Chemical changes usually involve the absorption or release of energy in the form of heat, light, or sound. The energy changes are essential for breaking and forming chemical bonds. In contrast, physical changes do not typically involve significant energy changes.
4. Phase changes: While physical changes involve alterations in the physical properties of a substance (such as its shape, size, or state of matter), chemical changes do not involve shifts in the phase of matter. Phase changes occur due to the rearrangement of molecules within a substance, while chemical changes result from the rearrangement and transformation of atoms.
It is important to note that not all the given options in the question are correct. Chemical changes are not always reversible, and their occurrence does not necessarily involve heat as some reactions can proceed without the need for heat input.
Chemical changes are different from physical changes in several ways:
1. Formation of new substances: A chemical change involves the formation of new substances with different chemical properties. The atoms and molecules rearrange to create new substances during a chemical change.
2. Irreversibility: Chemical changes are generally irreversible, meaning it is difficult or impossible to reverse the process and regain the original substances. Once a chemical change occurs, it is challenging to reverse the reaction and obtain the initial materials.
3. Involvement of heat: Chemical changes often involve the absorption or release of heat energy. Some chemical reactions require an input of heat energy, known as endothermic reactions, while others release heat energy, known as exothermic reactions.
4. Changes in phase of matter: Chemical changes may or may not involve changes in the phase of matter. For example, when water boils and turns into steam, it is a physical change. However, when iron rusts, it undergoes a chemical change as it reacts with oxygen in the presence of moisture to form iron oxide.
It's important to note that physical changes do not involve the formation of new substances or changes in the chemical identity of matter. Instead, physical changes are primarily related to changes in the physical properties or appearance of a substance, such as changes in shape, size, state of matter (e.g., solid to liquid), or phase transitions (e.g., melting, freezing, boiling). Physical changes are usually reversible and do not involve the formation of new substances.
Chemical changes and physical changes are two types of transformations that can occur in matter. Let me explain how they are different.
1. Heat involvement: Both chemical changes and physical changes can involve heat, but it is not a defining characteristic for either. Heat can be absorbed or released during both types of changes.
2. Reversibility: Physical changes are often reversible, meaning that the substance can be changed back to its original state. For example, melting and freezing of ice are physical changes that can be reversed. In contrast, chemical changes are typically irreversible. Once a chemical change occurs, the original substance(s) cannot be obtained again through simple means.
3. Formation of new substances: Chemical changes involve the formation of new substances with different chemical properties. For example, when wood is burned, it undergoes a chemical change and is converted into ash, smoke, and gases. These new substances have different chemical compositions than the original wood.
4. Phase changes: Physical changes may involve shifts in the phase of matter without any changes in the chemical composition. Examples of physical changes include melting, freezing, vaporizing, and condensing. These changes do not form new substances; they only alter the physical state of the matter.
To summarize, chemical changes involve the formation of new substances with different chemical properties, while physical changes do not alter the chemical composition and are often reversible.
how are chemical changes different from physical changes
A they involve heat
B they are reversible
C they form new substances
D they include shifts in the phase of matter
Chemical changes are different from physical changes in the following ways:
1. Formation of new substances: Chemical changes involve the formation of new substances with different chemical properties. During a chemical change, the atoms and molecules rearrange to create entirely new compounds or elements. Physical changes, on the other hand, do not result in the formation of new substances.
2. Reversibility: Chemical changes are typically irreversible. Once a chemical change occurs, it is challenging, if not impossible, to reverse the reaction and retrieve the original substances. In contrast, physical changes are often reversible, meaning that the substance can be changed back to its original state without any alteration in chemical properties.
3. Involvement of heat: While chemical changes may involve the absorption or release of heat energy, it is not a defining characteristic. Some chemical reactions require an input of heat energy (endothermic reactions), while others release heat energy (exothermic reactions). Similarly, physical changes can involve heat, but it is not a specific aspect that distinguishes them from chemical changes.
4. Phase changes: Physical changes encompass shifts in the phase of matter, such as melting, freezing, vaporization, and condensation. These changes alter the physical state of the substance without any modification in chemical composition. Chemical changes, on the other hand, do not typically involve shifts in the phase of matter.
To summarize, chemical changes involve the formation of new substances, are generally irreversible, may or may not involve heat, and do not include shifts in the phase of matter. Physical changes, in contrast, do not form new substances, can often be reversed, can involve heat, and include shifts in the phase of matter.
what's the answer???
The correct answer is:
Chemical changes involve the formation of new substances, while physical changes do not. Chemical changes are typically irreversible, while physical changes are often reversible. Heat involvement, formation of new substances, reversibility, and phase changes are all characteristics that can differentiate chemical changes from physical changes.
how does a balanced chemical equation demonstrate the law of conservation of mass
A. it shows that no atoms have been gained or lost during the reaction
B. it shows that only physical changes follow the law of conservation of mass
C. it shows that the properties of the elements stay the same after the reaction
D. it shows that all compounds remain bonded after the reaction
A. it shows that no atoms have been gained or lost during the reaction.
The law of conservation of mass states that mass cannot be created or destroyed in a chemical reaction. A balanced chemical equation provides a representation of the reaction, ensuring that the total number of atoms of each element is the same on both sides of the equation. This implies that no atoms have been gained or lost during the reaction, thus demonstrating the law of conservation of mass.