Which of the following could provide definitive evidence of a chemical reaction? Choose two correct answers. (1 point) A solid has dissolved in a liquid. Liquid water has frozen to form ice. A new substance, rust, has formed. A new substance, oxygen gas, has formed.
Place each change in the column that correctly identifies it as a chemical change or a physical change. (Drag and drop phrases into the correct columns.) (2 points) CHEMICAL CHANGES PHYSICAL CHANGES evaporating water #rusting iron #breaking glass neutralizing acid :: baking cake #boiling water
100 thx
So who is correct???
Bot GPT 3.5
The two correct answers that could provide definitive evidence of a chemical reaction are:
1. A new substance, rust, has formed.
2. A new substance, oxygen gas, has formed.
Chemical Changes:
- Rusting iron
- Baking cake
Physical Changes:
- Evaporating water
- Breaking glass
- Neutralizing acid
- Boiling water
To determine which of the given options could provide definitive evidence of a chemical reaction, we need to understand the characteristics of a chemical reaction.
A chemical reaction involves a change in the chemical composition of substances, resulting in the formation of new substances. Some key indicators of a chemical reaction are the production of a new substance, changes in color or odor, the release or absorption of heat or light, and the formation of a precipitate (a solid formed from a reaction between two liquids).
Based on these characteristics, the two options that could provide definitive evidence of a chemical reaction are:
1. A new substance, rust, has formed. Rust is the product of a chemical reaction between iron and oxygen in the presence of moisture. This chemical change results in the formation of a new compound, iron oxide.
2. A new substance, oxygen gas, has formed. Oxygen gas (O2) is produced through a chemical reaction, such as photosynthesis in plants or the decomposition of hydrogen peroxide. In this case, the formation of a new substance represents a chemical change.
Now let's categorize the given changes as either chemical or physical changes:
CHEMICAL CHANGES:
- Rusting iron: This involves the chemical reaction between iron and oxygen in the presence of moisture, resulting in the formation of iron oxide (rust).
- Baking cake: The process of baking a cake involves various chemical reactions, such as the leavening agents reacting with heat to produce carbon dioxide gas, which causes the cake to rise.
PHYSICAL CHANGES:
- Evaporating water: This is a physical change as it involves the conversion of liquid water to water vapor, without any change in its chemical composition.
- Breaking glass: Breaking glass is a physical change where the glass is physically fractured or broken into smaller pieces.
- Neutralizing acid: This process involves the reaction between an acid and a base to form a salt and water. However, it can be considered as more of a chemical change rather than a physical change as it involves the formation of new substances.
Boiling water is not provided in the options.
The two correct answers for providing definitive evidence of a chemical reaction are:
- A new substance, rust, has formed.
- A new substance, oxygen gas, has formed.
Chemical changes:
- Rusting iron
- Baking cake
Physical changes:
- Evaporating water
- Breaking glass
- Neutralizing acid
- Boiling water