Explain the difference between a color change in a chemical reaction and color change due to simple physical mixing of colors. Use example(s) and results from the activities in this lab. Gas bubbles appear when a carbonated beverage like soda is first opened. State whether this a is a physical or chemical change and explain your reasoning. A phase change is a type of physical change in which a substance transitions from one state or form of matter to a different state. List the activity in this experiment which demonstrated phase change. Name the substance and all the phases of matter you observed for that activity.
The Correct Answer and Explanation is:
Correct Answer:
1. Color Change – Chemical vs Physical:
A color change in a chemical reaction results from the formation of new substances with different properties. For example, when vinegar (acetic acid) reacts with baking soda (sodium bicarbonate), a new substance is formed and a color change may occur if an indicator is used. This color change indicates a chemical change because it shows that the original substances have undergone a transformation at the molecular level.
In contrast, a color change from physical mixing happens when two colored substances are blended without forming new materials. An example is mixing blue food coloring with yellow food coloring to produce green. This is a physical change since no new substance is created — the individual color particles are simply distributed evenly.
2. Gas Bubbles from Soda – Physical or Chemical Change:
The appearance of gas bubbles when opening a soda is a physical change. This occurs because carbon dioxide gas that was dissolved under pressure escapes into the air when the bottle is opened. The soda remains chemically the same before and after opening, and no new substances are formed. Therefore, it is not a chemical reaction but a physical release of gas.
3. Phase Change Activity in the Lab:
A phase change was demonstrated in the activity where ice was heated until it melted and then boiled. The substance involved was water (Hâ‚‚O). During this experiment, three phases of matter were observed:
- Solid phase: Ice at the beginning of the activity
- Liquid phase: Melted water after the ice turned to liquid
- Gas phase: Water vapor formed as the liquid boiled
This shows a physical change because the chemical composition of water remained the same throughout all the changes. Only the state of matter changed with the application of heat.
