D. 1 and 3 only
Observation 1 indicates a change in color, which is a common indication of a chemical reaction taking place. Observation 3 indicates a temperature increase, which is also indicative of a chemical reaction. Observation 2 simply states the volume of the combined liquids, and observation 4 states the density of the combined liquids, which are not necessarily direct indicators of a chemical reaction.
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.
3 and 4 only
B.
1 only
C.
1, 2, and 3 only
D.
1 and 3 only
1 answer