In experiment 3, what can the observations made during the reaction tell you about the nature of the reaction?

• A. They determine the purity of the products formed.
• B. They indicate whether the reaction is exothermic or endothermic based on temperature changes.
• C. They reveal the exact concentration of reactants used in the experiment.
• D. They show the atomic structure of the reactants.

Answer: (B)

Verified step by step guidance

1. Step 1: Understand that observations during a chemical reaction often include changes in temperature, color, gas evolution, or precipitate formation, which provide clues about the reaction's nature.
2. Step 2: Recognize that temperature changes during a reaction indicate whether the reaction releases heat (exothermic) or absorbs heat (endothermic).
3. Step 3: Note that determining the purity of products or exact concentrations typically requires additional analytical techniques beyond simple observation.
4. Step 4: Understand that atomic structure cannot be directly observed during a reaction; it requires specialized instruments like spectroscopy or crystallography.
5. Step 5: Conclude that the key information from observations in this context is the temperature change, which helps identify if the reaction is exothermic or endothermic.