Question

part b
label the small containers 1 and 2. add ¼ cup of room - temperature water to container 1 and ¼ cup of room - temperature vinegar to container 2. before continuing, make a hypothesis about each combination. will combining water and baking soda result in a chemical reaction? will combining vinegar and baking soda result in a chemical reaction?

Explanation:

For water and baking soda: Baking soda (sodium bicarbonate, $\ce{NaHCO_3}$) dissolves in water, which is a physical process (dissolution) with no new substance formed via a chemical reaction (though it dissociates into ions, but this is often considered a physical - chemical boundary case; typically, the mixing of water and baking soda is seen as mainly dissolution without a distinct chemical reaction like gas evolution or precipitate formation). So the hypothesis could be: Combining water and baking soda will not result in a chemical reaction (or will result in only dissolution, a physical process).

For vinegar and baking soda: Vinegar contains acetic acid ($\ce{CH_3COOH}$). The reaction between sodium bicarbonate ($\ce{NaHCO_3}$) and acetic acid is $\ce{NaHCO_3 + CH_3COOH
ightarrow CH_3COONa + H_2O + CO_2↑}$. This reaction produces carbon dioxide gas, water, and sodium acetate, so a new substance is formed. The hypothesis could be: Combining vinegar and baking soda will result in a chemical reaction (with gas evolution, etc.).

Answer:

• Hypothesis for water and baking soda: Combining water and baking soda will not result in a chemical reaction (or will result in a physical dissolution process without a significant chemical reaction).
• Hypothesis for vinegar and baking soda: Combining vinegar and baking soda will result in a chemical reaction (producing gas, water, and a new salt).