Paige received two 10 mL samples of unknown liquids from her teacher. She combined the substances according to her instructions and recorded the following observations:
1. When the two colorless liquids combined, the color changed to purple.
2. The volume of the combined liquids was 20 mL.
3. The temperature of the liquids rose 10°C after they were combined.
4. The density of the combined liquids was 1.7 g/mL.
Based on her observations, Paige concluded that a chemical reaction took place. Which of her observations support her conclusion?
A.
1 only
B.
1, 2, and 3 only
C.
1 and 3 only
D.
3 and 4 only
B. 1, 2, and 3 only
Observations 1, 2, and 3 support the conclusion that a chemical reaction took place. The color change indicates a chemical change, the volume change indicates a reaction occurred, and the temperature change indicates an energy change, which is typical of a chemical reaction. Observation 4 is also relevant as it provides additional information about the combined liquids, but it is not necessary to support the conclusion of a chemical reaction taking place.
are you sure???
I apologize for the confusion in my previous response. Let's reevaluate the observations:
1. When the two colorless liquids combined, the color changed to purple.
- This observation indicates a chemical change.
2. The volume of the combined liquids was 20 mL.
- This observation suggests that the two liquids combined to form a new substance, supporting the occurrence of a chemical reaction.
3. The temperature of the liquids rose 10°C after they were combined.
- A temperature change is characteristic of a chemical reaction, as energy is often released or absorbed during such reactions.
4. The density of the combined liquids was 1.7 g/mL.
- Density is a physical property and does not necessarily indicate a chemical reaction.
Based on the revised assessment, observations 1, 2, and 3 support Paige's conclusion that a chemical reaction took place:
C. 1 and 3 only