Which result occurs during an exothermic reaction

Question

Responses:

Light is released into the environment, while heat is absorbed.

Light and heat are absorbed from the environment.

Heat is released into the environment, while light is absorbed.

Light or heat are released into the environment.

Answer 1

During an exothermic reaction, the result is that heat is released into the environment, while light is absorbed. Therefore, the correct response is:

Light or heat are released into the environment.

Answer 2

Which event is an example of an endothermic reaction
Responses:

condensation

photosynthesis

burning wood

rusting of iron

Answer 3

The event that is an example of an endothermic reaction is photosynthesis. In photosynthesis, plants absorb energy from sunlight to convert carbon dioxide and water into glucose and oxygen, making it an endothermic process.

The other options listed are either exothermic reactions (like burning wood) or not classified as endothermic (like condensation or rusting of iron).

Answer 4

How is total reaction energy calculated
Responses:

product bond energy × reactant bond energy

reactant bond energy – product bond energy

product bond energy ÷ reactant bond energy

reactant bond energy + product bond energy

Answer 5

The total reaction energy is calculated using the following formula:

Reactant bond energy – Product bond energy.

This calculation determines the energy change of a reaction by comparing the energy required to break the bonds in the reactants with the energy released when new bonds are formed in the products.

Answer 6

When producing hydrogen iodide, the energy of the reactants is 581 kJ/mol, and the energy of the products is 590 kJ/mol. The equation is shown.
H2 + I2 → 2HI
What is the total energy of the reaction? Is this an endothermic or exothermic reaction
Responses:

–9 kJ/mol, exothermic

9 kJ/mol, exothermic

9 kJ/mol, endothermic

–9 kJ/mol, endothermic

Answer 7

To find the total energy of the reaction, we subtract the energy of the reactants from the energy of the products:

\[ \text{Total energy} = \text{Energy of products} - \text{Energy of reactants} \]

Given:

• Energy of reactants = 581 kJ/mol
• Energy of products = 590 kJ/mol

Now we can calculate:

\[ \text{Total energy} = 590 , \text{kJ/mol} - 581 , \text{kJ/mol} = 9 , \text{kJ/mol} \]

Since the total energy is positive, this indicates that the reaction absorbs energy from the surroundings. Therefore, it is an endothermic reaction.

The correct response is:

9 kJ/mol, endothermic.

Answer 8

Hydrogen bromide breaks down into diatomic hydrogen and bromine in the reaction shown.
2HBr → H2 + Br2
The energy of the reactant is 732 kJ/mol, and the energy of the products is 630 kJ/mol.
What is the total energy of the reaction? Is this reaction endothermic or exothermic
Responses:

–102 kJ/mol, endothermic

102 kJ/mol, endothermic

102 kJ/mol, exothermic

–102 kJ/mol, exothermic

Answer 9

To calculate the total energy of the reaction, we subtract the energy of the products from the energy of the reactants:

\[ \text{Total energy} = \text{Energy of products} - \text{Energy of reactants} \]

Given:

• Energy of reactants = 732 kJ/mol
• Energy of products = 630 kJ/mol

Now we calculate:

\[ \text{Total energy} = 630 , \text{kJ/mol} - 732 , \text{kJ/mol} = -102 , \text{kJ/mol} \]

Since the total energy is negative, this indicates that the reaction releases energy to the surroundings, making it an exothermic reaction.

The correct response is:

–102 kJ/mol, exothermic.