Evidence Of Physical & Chemical Changes

1. A chemical change cannot be reversed easily.

True

False

A chemical change involves a rearrangement of atoms and the formation of new substances. This process is often accompanied by the release or absorption of energy. Once a chemical change has occurred, it is usually difficult or impossible to reverse it and return the substances back to their original state. This is because the new substances formed have different properties and characteristics than the original substances. Therefore, the statement that a chemical change cannot be reversed easily is true.

Explanation

A chemical change involves a rearrangement of atoms and the formation of new substances. This process is often accompanied by the release or absorption of energy. Once a chemical change has occurred, it is usually difficult or impossible to reverse it and return the substances back to their original state. This is because the new substances formed have different properties and characteristics than the original substances. Therefore, the statement that a chemical change cannot be reversed easily is true.

2. Ms. Smith's class did a science experiment. The combined vinegar and baking soda in a cup and when the vinegar and baking soda touched each other, they fizzed and bubbled up. The cup over flowed with gases and bubbles. The following experiment was an example of what?

Chemical Change

Physical Change

Fusion Change

The science experiment described involves the combination of vinegar and baking soda, which results in a fizzy reaction and overflow of gases and bubbles. This indicates a chemical change, as a new substance is formed through a chemical reaction between the vinegar (acetic acid) and baking soda (sodium bicarbonate). The formation of carbon dioxide gas causes the fizzing and bubbling, indicating a chemical change rather than a physical change or fusion change.

Explanation

The science experiment described involves the combination of vinegar and baking soda, which results in a fizzy reaction and overflow of gases and bubbles. This indicates a chemical change, as a new substance is formed through a chemical reaction between the vinegar (acetic acid) and baking soda (sodium bicarbonate). The formation of carbon dioxide gas causes the fizzing and bubbling, indicating a chemical change rather than a physical change or fusion change.

3. Sarah put a sugar cube in a cup and watched what happened. The sugar cube dissolved. When Sarah came to check the cup again the next day, the sugar was back in the cup and the water had evaporated. Which of the follwing was experiment an example of?

Chemical Change

Physical Change

Fusion Change

The experiment described in the question is an example of a physical change. A physical change is a change in the form or state of matter without any new substances being formed. In this case, the sugar cube dissolved in water, which is a physical change as the sugar molecules dispersed evenly throughout the water. However, when the water evaporated, the sugar returned to its original form, indicating that no new substances were formed. Therefore, the correct answer is Physical Change.

Explanation

The experiment described in the question is an example of a physical change. A physical change is a change in the form or state of matter without any new substances being formed. In this case, the sugar cube dissolved in water, which is a physical change as the sugar molecules dispersed evenly throughout the water. However, when the water evaporated, the sugar returned to its original form, indicating that no new substances were formed. Therefore, the correct answer is Physical Change.

4. All of the following are evidence of a physical change except what?

The object can be reversed

A light is produced

The object freezes

The options provided describe different physical changes. The fact that an object can be reversed suggests that it undergoes a reversible change, which is a characteristic of physical changes. The object freezing is also a physical change, as it involves a change in state from a liquid to a solid. However, the production of light is not typically associated with physical changes, but rather with chemical changes or reactions. Therefore, the correct answer is that a light is produced.

Explanation

The options provided describe different physical changes. The fact that an object can be reversed suggests that it undergoes a reversible change, which is a characteristic of physical changes. The object freezing is also a physical change, as it involves a change in state from a liquid to a solid. However, the production of light is not typically associated with physical changes, but rather with chemical changes or reactions. Therefore, the correct answer is that a light is produced.

5. Which of the following is evidence of a chemical change?

A change in texture

A gas is produced

The new substance has conductivity

The presence of gas being produced is evidence of a chemical change because it indicates that a chemical reaction has occurred. In a chemical reaction, new substances are formed with different properties than the original substances. Gas production is often a result of the formation of new compounds or the release of gas molecules from a compound. This release of gas signifies a chemical change taking place.

Explanation

The presence of gas being produced is evidence of a chemical change because it indicates that a chemical reaction has occurred. In a chemical reaction, new substances are formed with different properties than the original substances. Gas production is often a result of the formation of new compounds or the release of gas molecules from a compound. This release of gas signifies a chemical change taking place.