Chemistry Se 11 B

During an endothermic reaction, heat content in the surroundings decreases because the reaction absorbs heat energy. This means that the reaction takes in heat from the surroundings, resulting in a decrease in the heat content of the surroundings.

The equation given, ∆EUniverse = ∆ESystem + ∆ESurroundings = 0, represents the principle of conservation of energy. This principle states that energy cannot be created or destroyed, only transferred or converted from one form to another. In this equation, the change in energy of the universe (∆EUniverse) is equal to the change in energy of the system (∆ESystem) plus the change in energy of the surroundings (∆ESurroundings), and the sum of these changes is always zero. This indicates that the total energy of the system and its surroundings remains constant, illustrating the conservation of energy.

When the average energy of a gas's particles decreases, it means that the gas is losing energy and becoming colder. This decrease in energy causes the gas particles to slow down and come closer together. As a result, the gas undergoes condensation, which is the process of gas particles transforming into a liquid state. During condensation, the gas particles release energy and form bonds with each other, resulting in the formation of liquid droplets.

High kinetic energy causes a change in state from liquid to gas because when the kinetic energy of the particles in a liquid increases, they gain enough energy to overcome the intermolecular forces holding them together. This leads to the particles moving more freely and eventually escaping from the liquid phase, resulting in the formation of a gas.

During photosynthesis, plants absorb energy from the surroundings to convert carbon dioxide and water into glucose and oxygen. This process is known as an endothermic reaction, meaning it requires energy input. As a result, the energy of the products (glucose and oxygen) is greater than the energy of the reactants (carbon dioxide and water).

The correct answer is "CH4(g)+2O2(g)→CO2(g)+2H2O(g)+heat" because the addition of "heat" as a product in the chemical equation indicates that the reaction is exothermic. In an exothermic reaction, heat is released as a product, resulting in an overall decrease in the energy of the system.