Reaction 2: vinegar and baking soda

The reaction between vinegar (which contains acetic acid) and baking soda (sodium bicarbonate) is a **chemical reaction**. Here are the reasons why this can be classified as such:

1. **New Substances Formed**: When vinegar and baking soda combine, they react to produce new substances, namely carbon dioxide gas (which is responsible for the bubbling and foaming), water, and sodium acetate. The formation of new products is a hallmark of a chemical reaction.

2. **Bubbling and Foaming**: The observation of bubbles and foam indicates that a gas is being produced. In this case, carbon dioxide gas is formed as a result of the reaction. Gas formation is another indicator of a chemical reaction.

3. **Change in Properties**: The properties of the original substances change significantly after the reaction. Vinegar is a clear liquid, and baking soda is a white powder; after they react, the resulting mixture exhibits bubbling and foam, which are not properties of the original substances.

4. **Irreversibility**: Although some reactions can be reversed, the reaction between vinegar and baking soda is generally not reversible under normal conditions. The production of gas and the changes in the solution indicate that the original substances cannot be easily recovered.

In conclusion, the reaction between vinegar and baking soda is a chemical reaction due to the transformation of reactants into new products, the production of gas, and the change in properties.

1-2 sentences

The reaction between vinegar and baking soda is a **chemical reaction** because it produces new substances, including carbon dioxide gas, which leads to bubbling and foaming. This transformation indicates a change in properties and the formation of products that are different from the original reactants.