During an endothermic reaction, heat content in the surroundings decreases because —

the reaction absorbs heat energy

energy is given off by the reaction

heat energy is destroyed during reactions

Chemistry SE 11 B

2.

Which of the following equations correctly shows that the combustion of methane is an exothermic reaction?

CH4(g) + 2O2(g) → CO2(g) + 2H2O(g)
Heat + CH4(g) + 2O2(g) → CO2(g) + 2H2O(g)
CH4(g)+2O2(g)+heat→CO2(g)+2H2O(g)
CH4(g)+2O2(g)→CO2(g)+2H2O(g)+heat

Correct Answer

A. CH4(g)+2O2(g)→CO2(g)+2H2O(g)+heat

Explanation

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.

Rate this question:

3.

Photosynthesis, the reaction plants use to make sugar, is an endothermic reaction. Which best describes the energy of the products and reactants in the photosynthesis reaction?

Energy is absorbed during the reaction, making the energy of the products greater than the energy of the reactants.
Energy is given off during the reaction, making the energy of the products greater than the energy of the reactants.
Energy is absorbed during the reaction, making the energy of the reactants greater than the energy of the products.
Energy is given off during the reaction, making the energy of the reactants greater than the energy of the products.

Correct Answer

A. Energy is absorbed during the reaction, making the energy of the products greater than the energy of the reactants.

Explanation

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).

Rate this question:

4.

Which of the following causes a change in state from liquid to gas?

High kinetic energy
A chemical reaction
Hydrogen bonding
Temperature at freezing point

Correct Answer

A. High kinetic energy

Explanation

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.

Rate this question:

5.

What process takes place when the average energy of a gas’s particles decreases?

Condensation
Vaporization
Boiling
Melting

Correct Answer

A. Condensation

Explanation

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.

Rate this question:

6.

∆E_Universe= ∆E_{System +}∆E_Surroundings= 0

Conservation of energy.
Conservation of mass.
Definite composition.
Multiple proportions.

Correct Answer

A. Conservation of energy.

Explanation

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.

Rate this question:

Chemistry Se 11 B

During an endothermic reaction, heat content in the surroundings decreases because —

Quiz Preview

Which of the following equations correctly shows that the combustion of methane is an exothermic reaction?

Photosynthesis, the reaction plants use to make sugar, is an endothermic reaction. Which best describes the energy of the products and reactants in the photosynthesis reaction?

Which of the following causes a change in state from liquid to gas?

What process takes place when the average energy of a gas’s particles decreases?

∆E_Universe= ∆E_{System +}∆E_Surroundings= 0