Energy Changes Flashcards
What is an exothermic reaction?
An exothermic reaction is one in which the products have less energy than the reactants, resulting in the release of energy to the surroundings, typically as heat.
What are common examples of exothermic reactions?
Common examples of exothermic reactions include combustion reactions, neutralization reactions, and most oxidation reactions.
How is energy represented in a reaction profile for exothermic reactions?
In a reaction profile for exothermic reactions, reactants are placed on the left and products lower on the right to indicate that products have less energy.
What is an endothermic reaction?
An endothermic reaction is one that absorbs heat energy from the surroundings, resulting in products that have more energy than the reactants.
What is an example of an endothermic reaction?
An example of an endothermic reaction is the thermal decomposition of calcium carbonate into calcium oxide and carbon dioxide
How is energy represented in a reaction profile for endothermic reactions?
In a reaction profile for endothermic reactions, reactants are on the left and products higher on the right to indicate that products have more energy.
What is activation energy?
Activation energy is the minimum amount of energy required for reactant particles to collide and react.
How does activation energy affect reaction profiles?
Higher activation energy results in a higher curve on the reaction profile, while lower activation energy results in a lower curve.
What is the significance of activation energy in exothermic reactions?
Even in exothermic reactions, activation energy is necessary to initiate the reaction despite the overall energy release.
What does the y-axis represent in a reaction profile?
The y-axis in a reaction profile represents the total energy of the molecules involved in the reaction.
What does the x-axis represent in a reaction profile?
The x-axis in a reaction profile represents the progress of the reaction from reactants to products.
How does energy transfer occur in exothermic reactions?
In exothermic reactions, energy is transferred to the surroundings, primarily in the form of heat.
What is the difference in energy levels between reactants and products in exothermic reactions?
In exothermic reactions, the products have lower energy than the reactants, indicating energy release.
What is the difference in energy levels between reactants and products in endothermic reactions?
In endothermic reactions, the products have higher energy than the reactants, indicating energy absorption.
Why is it important to understand chemical energy storage?
Understanding chemical energy storage helps explain how different chemicals release or absorb energy during reactions.
What role does heat play in endothermic reactions?
Heat must be supplied to endothermic reactions to enable the absorption of energy necessary for the reaction to occur.
What happens to temperature in exothermic reactions?
In exothermic reactions, the temperature of the surroundings increases as heat is released.
What is the relationship between activation energy and reaction rate?
Higher activation energy typically results in a slower reaction rate, as more energy is required to initiate the reaction.
What is the energy difference labeled in endothermic reaction profiles?
The energy difference in endothermic reaction profiles is labeled as the energy absorbed from the surroundings.
What happens to energy in a sealed container during an exothermic reaction?
In a sealed container during an exothermic reaction, energy is released as heat, causing an increase in temperature.
What is the significance of the peak in a reaction profile?
The peak in a reaction profile represents the maximum energy level, where activation energy is required for the reaction to proceed.
How can the energy of reactants and products be compared?
The total energy of reactants can be compared to the total energy of products to determine if the reaction is exothermic or endothermic.
What happens when activation energy is lowered?
When activation energy is lowered, the curve on the reaction profile becomes lower, indicating that less energy is needed to initiate the reaction.
How do combustion reactions exemplify exothermic reactions?
Combustion reactions exemplify exothermic reactions as they release significant amounts of heat and light energy when fuels are burned.
What is the role of a Bunsen burner in endothermic reactions?
A Bunsen burner provides the necessary heat energy to drive endothermic reactions, such as the decomposition of calcium carbonate.
What does it mean if a reaction profile shows a downward slope?
A downward slope in a reaction profile indicates that the products have lower energy than the reactants, characteristic of exothermic reactions.
What does it mean if a reaction profile shows an upward slope?
An upward slope in a reaction profile indicates that the products have higher energy than the reactants, characteristic of endothermic reactions.
What is the difference between exothermic and endothermic reactions?
Exothermic reactions release energy to the surroundings, while endothermic reactions absorb energy from the surroundings.
What do reaction profiles illustrate?
Reaction profiles illustrate the total energy of molecules during a reaction’s progress, with energy plotted on the y-axis and reaction progress on the x-axis.
How is energy represented in an exothermic reaction profile?
In an exothermic reaction profile, reactants are placed on the left and products lower on the right, indicating that products have less energy.
What types of reactions are typically exothermic?
Common exothermic reactions include combustion, neutralization, and most oxidation reactions.
What happens to energy during an endothermic reaction?
In an endothermic reaction, energy is absorbed from the surroundings, resulting in products that have more energy than the reactants.
How is energy represented in an endothermic reaction profile?
In an endothermic reaction profile, reactants are on the left and products are higher on the right, indicating that products have more energy.
What is the energy released by forming one H-Cl bond?
The energy released by forming one H-Cl bond is 431 kJ/mol.
How do you determine if a reaction is exothermic or endothermic?
To determine if a reaction is exothermic or endothermic, compare the total energy required to break bonds with the total energy released when bonds form.
Is breaking bonds an endothermic or exothermic process?
Breaking bonds is an endothermic process because it requires energy from the surroundings.
What does a positive overall energy change indicate
A positive overall energy change indicates that the reaction is endothermic, meaning energy is absorbed from the surroundings.
What is bond energy?
Bond energy is the amount of energy required to break one mole of a particular covalent bond.
What does a negative overall energy change indicate?
A negative overall energy change indicates that the reaction is exothermic, meaning energy is lost to the surroundings.
In the reaction H2 + Cl2 → 2HCl, what bonds are formed?
In this reaction, two H-Cl bonds are formed.
What is Avogadro’s constant?
Avogadro’s constant is 6.02 x 10^23, representing the number of particles in one mole.
How do you calculate total energy released by forming bonds in a reaction?
Total energy released by forming bonds is the sum of the bond energies of all bonds formed.
What is the energy required to break one H-H bond?
The energy required to break one H-H bond is 436 kJ/mol.
What is the energy balance in an endothermic reaction?
In an endothermic reaction, the energy required to break bonds exceeds the energy released by forming bonds.
Is bond formation an endothermic or exothermic process?
Bond formation is an exothermic process because it releases energy to the surroundings.
What is the overall energy change equation?
The overall energy change is calculated as the energy required to break bonds minus the energy released by forming bonds.
What is the energy balance in an exothermic reaction?
In an exothermic reaction, the energy released by forming bonds exceeds the energy required to break bonds.
