Which observation most likely indicates that only a chemical change has taken place
To determine if a chemical change has occurred, you need to look for specific characteristics and observations. The following observation is most likely to indicate that only a chemical change has taken place: the formation of new substances or products.
In a chemical change, the chemical composition of the substances involved changes, leading to the formation of new substances with different properties. This is usually accompanied by observable signs such as:
1. Color change: If you start with one color and end up with a completely different color, it suggests a chemical change. For example, when iron rusts, it changes from a shiny metallic silver color to a reddish-brown color.
2. Formation of gas: If you notice the production of bubbles or a gas being released, it indicates a chemical change. An example is the reaction between vinegar and baking soda, which creates carbon dioxide gas, causing a foaming effect.
3. Temperature change: If there is a significant change in temperature, it can indicate a chemical change. For instance, adding water to anhydrous copper sulfate causes a temperature increase as the compound hydrates.
4. Precipitate formation: A precipitate is a solid that forms from a liquid solution. When two soluble substances are mixed together and form an insoluble solid, it suggests a chemical change. An example is the reaction between silver nitrate and sodium chloride, which produces a white precipitate of silver chloride.
Remember, a single observation may not conclusively determine whether it is a chemical change. It is essential to consider multiple signs together to make a more accurate determination.