Describe the to type of energy changes that can occur in a chemical reaction Thanks
temperature change, (endothermic an exothermic) color change
evidence of chemical reactions also include bubbling and fizzing
In a chemical reaction, there are two types of energy changes that can occur: endothermic and exothermic.
1. Endothermic: This type of reaction absorbs energy from its surroundings. In other words, the reactants have lower energy than the products. As a result, heat is taken in from the surroundings, making the surroundings feel colder. This energy can be in the form of heat, light, or electrical energy. To determine if a reaction is endothermic, you can look for signs such as a decrease in temperature, absorption of heat, or the need for external energy input.
An example of an endothermic reaction is the process of photosynthesis. In this reaction, plants absorb energy from sunlight and convert it into chemical energy, stored in molecules such as glucose. The overall reaction is:
6CO2 + 6H2O + energy (sunlight) → C6H12O6 + 6O2
2. Exothermic: In contrast to endothermic reactions, exothermic reactions release energy into the surroundings. The reactants have higher energy than the products, resulting in a heat release. As a result, the surroundings feel warmer. This energy is usually given off in the form of heat but can also include other forms such as light or sound. To identify an exothermic reaction, you can look for signs such as an increase in temperature, heat release, or ignition.
An example of an exothermic reaction is the combustion of gasoline. In this reaction, gasoline reacts with oxygen to produce carbon dioxide, water, and energy in the form of heat and light:
2C8H18 + 25O2 → 16CO2 + 18H2O + energy
In both cases, whether a reaction is endothermic or exothermic can be determined by measuring the temperature change of the system during the reaction using a thermometer or by observing if heat is absorbed or released.