Question

Students performed a lab investigation on chemical reactions. the students put on goggles and plastic gloves and then followed these steps. 1. pour 150 milliliters of vinegar into a beaker. 2. place a thermometer in the vinegar and record measurements. 3. add a piece of steel wool to the beaker. 4. observe and record thermometer measurements. 5. remove the steel wool from the beaker. 6. use tweezers to pull strands of the steel wool apart and observe changes. Which observation would indicate that a chemical reaction occurred?

a. the vinegar took the shape of the container in step 1.
b the steel wool sank into the vinegar in step 3.
c the temperature of the vinegar increased during step 4.
d the steel wool changed shape during step 6.

Answer 1

An increase in temperature during step 4 of the experiment would indicate that a chemical reaction has occurred, as it signifies energy being released.

Step-by-step explanation:

Which observation would indicate that a chemical reaction occurred during the lab investigation?

Among the options given, the one that indicates a chemical reaction is c. the temperature of the vinegar increased during step 4. This is an observable factor that suggests a chemical reaction because all chemical changes involve a transfer of energy. An increase in temperature indicates that energy is being released during a reaction. This is different from a physical change, which may also involve a change in energy, but does not result in a new substance being formed. Observations such as color change, gas production, and formation of a solid precipitate are also indicators of a chemical reaction.