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Questions and Answers
What happens to the reaction rate if the specific rate constant (k) is large?
What happens to the reaction rate if the specific rate constant (k) is large?
- The reaction is slower.
- The reaction remains the same speed.
- The reaction does not occur.
- The reaction is faster. (correct)
The exponents in the rate equation for a chemical reaction generally relate to the coefficients in the chemical equation.
The exponents in the rate equation for a chemical reaction generally relate to the coefficients in the chemical equation.
False (B)
What is the unit of the specific rate constant (k) for a second order reaction?
What is the unit of the specific rate constant (k) for a second order reaction?
L/mol.time
For a first order reaction, the rate law is: Rate = k[X]____.
For a first order reaction, the rate law is: Rate = k[X]____.
Match the order of reaction with its corresponding unit of specific rate constant (k):
Match the order of reaction with its corresponding unit of specific rate constant (k):
If the concentration of reactant X is halved in a first order reaction, what happens to the reaction rate?
If the concentration of reactant X is halved in a first order reaction, what happens to the reaction rate?
In a single-step reaction with a single activated complex, the exponents in the rate law are equal to the coefficients.
In a single-step reaction with a single activated complex, the exponents in the rate law are equal to the coefficients.
What defines how the rate is affected by the concentration of a reactant in a reaction?
What defines how the rate is affected by the concentration of a reactant in a reaction?
What does the law of conservation of energy state?
What does the law of conservation of energy state?
Chemical potential energy is the energy stored in a substance due to its physical state.
Chemical potential energy is the energy stored in a substance due to its physical state.
What happens to heat in an exothermic reaction?
What happens to heat in an exothermic reaction?
Heat is energy that is flowing from a ______ object to a ______ object.
Heat is energy that is flowing from a ______ object to a ______ object.
Match the following units with their corresponding measurement:
Match the following units with their corresponding measurement:
What is the main purpose of calorimetry?
What is the main purpose of calorimetry?
A coffee cup calorimeter can be used for high temperature reactions.
A coffee cup calorimeter can be used for high temperature reactions.
What type of calorimeter is typically used to measure the caloric content of food?
What type of calorimeter is typically used to measure the caloric content of food?
A calorimeter is an insulated device used for measuring the amount of heat absorbed or released during a __________.
A calorimeter is an insulated device used for measuring the amount of heat absorbed or released during a __________.
Match the calorimeter type with its description:
Match the calorimeter type with its description:
What component is essential for the functioning of a bomb calorimeter during reaction initiation?
What component is essential for the functioning of a bomb calorimeter during reaction initiation?
Water absorbs heat in both types of calorimeters during a reaction.
Water absorbs heat in both types of calorimeters during a reaction.
Why can't a coffee cup calorimeter be used for reactions that involve gases?
Why can't a coffee cup calorimeter be used for reactions that involve gases?
Which of the following is a product in the given reaction mechanism?
Which of the following is a product in the given reaction mechanism?
The intermediate in the first reaction mechanism is identified as WR.
The intermediate in the first reaction mechanism is identified as WR.
Identify the catalyst in the given reaction mechanism.
Identify the catalyst in the given reaction mechanism.
The overall reaction can be summarized as ______ + W → S.
The overall reaction can be summarized as ______ + W → S.
Match the following terms with their corresponding definitions:
Match the following terms with their corresponding definitions:
Which step is considered the rate-determining step in the first mechanism?
Which step is considered the rate-determining step in the first mechanism?
WR is an intermediate in the second reaction mechanism.
WR is an intermediate in the second reaction mechanism.
List all the reactants in the first reaction mechanism.
List all the reactants in the first reaction mechanism.
Which substance has a higher specific heat capacity when substance X's temperature changes twice as much as substance Y's?
Which substance has a higher specific heat capacity when substance X's temperature changes twice as much as substance Y's?
The formula for calculating heat absorbed is given by q = m × c × ∆T.
The formula for calculating heat absorbed is given by q = m × c × ∆T.
What is the specific heat capacity (c) of water?
What is the specific heat capacity (c) of water?
The change in temperature (∆T) is calculated by the formula ΔT = T ______ - T ______.
The change in temperature (∆T) is calculated by the formula ΔT = T ______ - T ______.
How much heat is absorbed by 34.0 g of water when heated from 30.0℃ to 60.0℃?
How much heat is absorbed by 34.0 g of water when heated from 30.0℃ to 60.0℃?
A substance with a higher mass will always have a higher temperature change.
A substance with a higher mass will always have a higher temperature change.
If a 50.0 g sample of water is cooled from 74.0℃ to 40.0℃, how much heat is released?
If a 50.0 g sample of water is cooled from 74.0℃ to 40.0℃, how much heat is released?
Match the following calculations with their correct outcomes:
Match the following calculations with their correct outcomes:
Study Notes
Reaction Rate and Specific Rate Constant
- Larger the value of the specific rate constant (k), the faster the reaction
- The value of k is large if the products form quickly
- The value of k is small if the products form slowly
Rate Equation and Chemical Equation
- In general, the exponents in the rate equation do not relate to the coefficients in the chemical equation
- For single-step reactions with a single activated complex, the exponents are equal to the coefficients
Units of the Rate Constant (k)
- Zero order reaction: mol/L.time
- First order reaction: time‒1
- Second order reaction: M‒1.time‒1
- Third order reaction: M‒2.time‒1
First Order Reaction
- Rate law of a first order reaction: Rate = k[X]
- The rate changes in the same proportion as the concentration of the reactant ([X])
- The rate constant (k) is equal to the slope of the line in a graph of concentration against time
Law of Conservation of Energy
- Energy can be converted from one form to another, but it is neither created nor destroyed
Chemical Potential Energy
- Energy stored in a substance due to its composition
Exothermic and Endothermic Reactions
- In exothermic reactions, chemical potential energy is converted to heat and released
- In endothermic reactions, heat is absorbed and converted to chemical potential energy
Temperature and Heat
- Temperature: Average kinetic energy of particles in a sample of matter
- Heat (q): Energy flowing from a warmer object to a cooler object
Units of Temperature and Heat
- Temperature: Kelvin (K) and Celsius (℃)
- Heat: Joule (J), calorie (c), and Calorie (Cal)
Specific Heat Capacity
- The amount of heat required to raise the temperature of one gram of a substance by one degree Celsius
- The substance with a greater specific heat capacity undergoes a smaller temperature change
Calculating Heat Absorbed or Released
- Formula: q = m × c × ∆T
- q = Heat absorbed or released (Joules)
- m = Mass of the substance (grams)
- c = Specific heat capacity of the substance (J/g.℃)
- ∆T = Change in temperature (℃)
Calorimetry
- Measurement of heat flow into or out of a system during chemical and physical processes
Calorimeter
- Insulated device used to measure the amount of heat absorbed or released during a chemical or physical process
Coffee-cup and Bomb Calorimeters
- Coffee-cup calorimeter: Used to measure heat flow in chemical solutions.
- Limitations: Cannot be used for reactions involving gases or high temperatures.
- Bomb calorimeter: Used to measure heat flow for solids with low to high temperature reactions (like combustion reactions).
- Used to determine caloric content of food.
Reaction Mechanisms
- Series of steps involved in a chemical reaction
- Each step represents an elementary reaction
- Slowest step is the rate-determining step
Identifying Components of a Reaction Mechanism
- Reactants: Species consumed in the overall reaction
- Products: Species formed in the overall reaction
- Catalyst: Substance that speeds up the reaction without being consumed
- Intermediates: Species formed and then consumed in the reaction mechanism
- Rate-determining step: The slowest step in the reaction mechanism
Energy Diagram and Reaction Mechanism
- Energy diagram: Illustrates the energy changes that occur during a reaction, showing the transition states and the activation energy of each step
- Transition state: The highest energy point on the reaction pathway
- Activation energy: The minimum energy required for reactants to reach the transition state and form products
- Rate-determining step: The step with the highest activation energy
- Products
- Reactants and products can be identified by their energy levels
- Intermediate: Species that are formed and then consumed in the reaction (valley on the energy diagram)
- Activated complex: The unstable arrangement of atoms at the transition state (peak on the energy diagram)
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Description
Test your knowledge on chemical kinetics, including the specific rate constant and rate equations. Explore the significance of reaction order and the units of rate constants for various reactions. This quiz covers key concepts that are essential for understanding reaction rates and their implications in chemistry.
