Question

state any two observations in an activity suggesting the occurrence of a chemical reaction

Answer 1

A chemical change can be confirmed by any of the following observations:
Change in temperature
Evolution of gas
For example: Calcium oxide reacts vigorously with water to produce calcium hydroxide. During this process, a large amount of heat is also evolved, which increases the temperature of the system. This confirms that a chemical reaction has taken place. Also, when calcium carbonate is heated, it decomposes to form calcium oxide and carbon dioxide. In this reaction, calcium carbonate breaks down to form calcium oxide and carbon dioxide. Here, evolution of the gas (carbon dioxide) confirms that a chemical reaction has taken

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Answer 2

Answer:

When two or more molecules hit with the proper orientation and enough force to create a new product, the process is known as a chemical reaction. In this procedure, bonds between atoms are broken and formed.

Explanation:

A chemical reaction may have occurred in an activity if the following observations are made:

Changes in temperature, color, a gas's evolution, condition, and other factors.

i) Calcium hydroxide is created when water and calcium oxide react violently. A significant quantity of heat is also released during this process, raising the system's temperature. This demonstrates that there was a chemical reaction.

                CaO + H₂O → Ca(OH)₂

ii) When heated, calcium carbonate also breaks down into calcium oxide and carbon dioxide.

Here, the gas' evolution (carbon dioxide) proves that a chemical reaction has occurred.

               CaCO₃ → CaO + CO₂↑

Hence the 2 observations in an activity suggesting the occurrence of a chemical reaction is explained above.

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