A researcher conducts two separate experiments in a laboratory.
In Experiment 1, a chunk of solid carbon dioxide is submerged in room-temperature water, producing vigorous bubbling.
In Experiment 2, a piece of solid calcium metal is submerged in room-temperature water, which also produces vigorous bubbling, along with a noticeable increase in temperature and the formation of a cloudy white suspension.
Based on the evidence provided, which of the following best classifies the two experiments and correctly identifies the primary gas generating the bubbles in the experiment that represents a chemical change?
- Experiment 1 is a physical change and Experiment 2 is a chemical change; the gas released in Experiment 2 is hydrogen ().Answer
- BBoth experiments represent chemical changes; the gas released in Experiment 1 is carbon dioxide () and the gas released in Experiment 2 is oxygen ().
- CExperiment 1 is a physical change and Experiment 2 is a chemical change; the gas released in Experiment 2 is oxygen ().
- DExperiment 1 is a chemical change and Experiment 2 is a physical change; the gas released in Experiment 1 is carbon dioxide ().
Answer
Experiment 1 is a physical change and Experiment 2 is a chemical change; the gas released in Experiment 2 is hydrogen ().
The correct answer accurately identifies that solid carbon dioxide sublimating into carbon dioxide gas is a physical change because the chemical structure does not change. It also accurately recognizes that calcium reacting with water is a chemical change that produces a new solid compound (calcium hydroxide) and hydrogen gas ().
Step-by-Step Solution
Key Concept
Distinguishing physical phase changes from chemical reactions and predicting products of metal-water reactions.
Estimated Time:1m 30s