Which of the following is a reliable way to observe that a chemical change has occurred when two substances come in contact with one another?(1 point)
observe a color change
monitor for the release of a gas
test for the release of heat
conduct a test to determine the chemical makeup of the molecules
All of the options listed can be reliable ways to observe that a chemical change has occurred when two substances come in contact with each other. However, the most immediate and easily observed changes would be a color change or the release of a gas.
The reliable ways to observe that a chemical change has occurred when two substances come in contact with each other are:
1. Observe a color change: If the two substances combine and result in a noticeable change in color, it is likely that a chemical change has occurred. For example, if a clear solution turns red or a white solid turns black, it suggests a chemical reaction has taken place.
2. Monitor for the release of a gas: When certain chemical reactions occur, they may produce gas as a byproduct. Bubbles or the formation of a gas can indicate a chemical change. For instance, the fizzing that occurs when vinegar reacts with baking soda is an example of a gas being released.
3. Test for the release of heat: Some chemical reactions are exothermic, meaning they release heat. If there is a noticeable temperature change when the substances are combined, it suggests a chemical change. This might be done by feeling the solution or using a thermometer to measure any changes in temperature.
4. Conduct a test to determine the chemical makeup of the molecules: This method involves testing the substances before and after the reaction to determine if a change has occurred. By analyzing the chemical composition, it is possible to identify any new or different substances formed during the reaction. This could involve techniques like spectroscopy or chromatography.
It is important to note that these methods can be used in combination to provide more conclusive evidence of a chemical change.