To start chemical reactions, it is necessary to create the appropriate conditions for this:
- bringing substances into close contact.
- heating of substances to a certain temperature (the temperature of the chemical reaction must be suitable).
According to the signs of chemical reactions, it is possible to judge whether a chemical reaction has passed between the reagents or not. Here are examples of signs of chemical reactions:
- Color change (light iron, for example, in moist air is covered with a brown coating, as a result of the chemical reaction of the interaction of iron and oxygen).
- Precipitation (if you suddenly pass carbon dioxide through the lime solution, we get a white insoluble precipitate of calcium carbonate).
- Gas release (if you drop citric acid on baking soda, you will get the release of carbon dioxide).
- Formation of weakly dissociated substances (all reactions that result in the formation of water).
- Luminescence of the solution (an example here is the reactions that occur with a solution of luminol, which emits light during chemical reactions).