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Questions and Answers
What is the correct description of an activated complex?
What is the correct description of an activated complex?
If the enthalpy of the reactants is $60kJ$ and the enthalpy of the products is $20kJ$, what is the change in enthalpy $(\Delta H)$ of the reaction and is the reaction exothermic or endothermic?
If the enthalpy of the reactants is $60kJ$ and the enthalpy of the products is $20kJ$, what is the change in enthalpy $(\Delta H)$ of the reaction and is the reaction exothermic or endothermic?
In an exothermic reaction, how do the energy levels of the reactants and products compare?
In an exothermic reaction, how do the energy levels of the reactants and products compare?
In a reaction energy diagram, which of the following represents the activation energy?
In a reaction energy diagram, which of the following represents the activation energy?
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If a catalyst is added to a reaction, what is the main effect on an energy diagram?
If a catalyst is added to a reaction, what is the main effect on an energy diagram?
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In the reaction Al + 3CuCl → AlCl3 + 3Cu, if the amount of Al decreases by 6 mol in two seconds, what is the corresponding change in the amount of Cu?
In the reaction Al + 3CuCl → AlCl3 + 3Cu, if the amount of Al decreases by 6 mol in two seconds, what is the corresponding change in the amount of Cu?
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Given the reaction 2KBr + Mg → MgBr2 + 2K, if 12 mol of MgBr2 is produced in 2 seconds, how much K is produced in the same time?
Given the reaction 2KBr + Mg → MgBr2 + 2K, if 12 mol of MgBr2 is produced in 2 seconds, how much K is produced in the same time?
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In a reaction where reactants X2 and Y2 form 2XY, what is the change in enthalpy if the energy of the reactants is 50kJ, and the energy of the products is 100kJ?
In a reaction where reactants X2 and Y2 form 2XY, what is the change in enthalpy if the energy of the reactants is 50kJ, and the energy of the products is 100kJ?
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In the reaction 2KBr + Mg → MgBr2 + 2K, if 20 mol of KBr reacts, what amount of Mg will be needed?
In the reaction 2KBr + Mg → MgBr2 + 2K, if 20 mol of KBr reacts, what amount of Mg will be needed?
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If the transition state energy for a reaction is 150kJ and the reactants have an energy of 50kJ, what is the activation energy?
If the transition state energy for a reaction is 150kJ and the reactants have an energy of 50kJ, what is the activation energy?
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Consider the reaction: Al + 3CuCl → AlCl3 + 3Cu. If at 6 seconds there are 22 mol of Al, and at 8 seconds there are 18 mol of Al, what is the average rate of change of [Al] over that period?
Consider the reaction: Al + 3CuCl → AlCl3 + 3Cu. If at 6 seconds there are 22 mol of Al, and at 8 seconds there are 18 mol of Al, what is the average rate of change of [Al] over that period?
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For a reaction with reactants at 100kJ and products at 25kJ, what is the enthalpy change?
For a reaction with reactants at 100kJ and products at 25kJ, what is the enthalpy change?
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A reaction has an enthalpy change of -20kJ. Is it endothermic or exothermic?
A reaction has an enthalpy change of -20kJ. Is it endothermic or exothermic?
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What effect does increasing the concentration of reactants typically have on the rate of a chemical reaction?
What effect does increasing the concentration of reactants typically have on the rate of a chemical reaction?
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Which reaction will proceed faster, one with an activation energy of $10kJ$ or one with an activation energy of $150kJ$?
Which reaction will proceed faster, one with an activation energy of $10kJ$ or one with an activation energy of $150kJ$?
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How does decreasing the temperature affect the rate of a chemical reaction?
How does decreasing the temperature affect the rate of a chemical reaction?
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What is the effect of increasing the volume on the rate of reaction?
What is the effect of increasing the volume on the rate of reaction?
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If a reaction has reactants with a potential energy of 200kJ and products with a potential energy of 100kJ, what is the change in enthalpy?
If a reaction has reactants with a potential energy of 200kJ and products with a potential energy of 100kJ, what is the change in enthalpy?
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In a potential energy diagram for a reaction, which of the following is not labeled on the Y-axis?
In a potential energy diagram for a reaction, which of the following is not labeled on the Y-axis?
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Which of the following does NOT typically increase the rate of reaction?
Which of the following does NOT typically increase the rate of reaction?
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A reaction has an initial potential energy of 35kJ. It reaches a transition state with 45kJ of energy and finishes with 15kJ of energy. How much energy would a catalyst use, with the assumption it lowers the activation energy by 50%?
A reaction has an initial potential energy of 35kJ. It reaches a transition state with 45kJ of energy and finishes with 15kJ of energy. How much energy would a catalyst use, with the assumption it lowers the activation energy by 50%?
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In a chemical reaction, if the concentration of a substance decreases over time, what is it classified as?
In a chemical reaction, if the concentration of a substance decreases over time, what is it classified as?
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Given a reaction where the rate of N$_2$O$_5$ consumption is 2.4 M/hour, and the reaction is 2N$_2$O$_5$ → 4NO$_2$ + O$_2$, at what rate is NO$_2$ formed?
Given a reaction where the rate of N$_2$O$_5$ consumption is 2.4 M/hour, and the reaction is 2N$_2$O$_5$ → 4NO$_2$ + O$_2$, at what rate is NO$_2$ formed?
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If the rate of change of [CH$_4$] is -1.25 mol/s, and the reaction is CH$_4$ + 2O$_2$ → CO$_2$ + 2H$_2$O, what is the rate of change of [O$_2$]?
If the rate of change of [CH$_4$] is -1.25 mol/s, and the reaction is CH$_4$ + 2O$_2$ → CO$_2$ + 2H$_2$O, what is the rate of change of [O$_2$]?
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Which of the following best describes the term 'instantaneous rate'?
Which of the following best describes the term 'instantaneous rate'?
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In the reaction 24NH$_3$ + 5O$_2$ → 4NO + 6H$_2$O, which of the following represents the correct rate expression relationship for NH$_3$ compared to others?
In the reaction 24NH$_3$ + 5O$_2$ → 4NO + 6H$_2$O, which of the following represents the correct rate expression relationship for NH$_3$ compared to others?
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Consider a graph of concentration vs. time for a reaction. For a reactant, how will the slope of the tangent line change as the reaction progresses?
Consider a graph of concentration vs. time for a reaction. For a reactant, how will the slope of the tangent line change as the reaction progresses?
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If a reaction has an instantaneous rate of 0.00469 g/s at the beginning, but decreases with time, what information does the average rate provide?
If a reaction has an instantaneous rate of 0.00469 g/s at the beginning, but decreases with time, what information does the average rate provide?
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In the reaction CH$_4$ + 2O$_2$ → CO$_2$ + 2H$_2$O, if the rate of consumption of CH$_4$ is 1.25 mol/s, what is the rate of formation of H$_2$O?
In the reaction CH$_4$ + 2O$_2$ → CO$_2$ + 2H$_2$O, if the rate of consumption of CH$_4$ is 1.25 mol/s, what is the rate of formation of H$_2$O?
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In the reaction $N_{2(g)} + 2O_{2(g)} \rightarrow 2NO_{2(g)}$, if the concentration of $NO_2$ increases by $0.45M$ over 3 minutes, what is the reaction rate of $NO_2$ in $M/s$?
In the reaction $N_{2(g)} + 2O_{2(g)} \rightarrow 2NO_{2(g)}$, if the concentration of $NO_2$ increases by $0.45M$ over 3 minutes, what is the reaction rate of $NO_2$ in $M/s$?
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For the reaction $Li^+ + NO_3^- \rightarrow LiNO_3$, if the initial amount of $Li^+$ is 5g and after 30 seconds it is 0g, what is the reaction rate of $Li^+$?
For the reaction $Li^+ + NO_3^- \rightarrow LiNO_3$, if the initial amount of $Li^+$ is 5g and after 30 seconds it is 0g, what is the reaction rate of $Li^+$?
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Which of these is NOT a valid way to measure the reaction rate of the reaction below? $Cu(s) + 4H^+(aq) + 4NO_3^-(aq) \rightarrow Cu^{+2}(aq) + 2NO_3^-(aq) + 2NO_2(g) + 2H_2O(l)$
Which of these is NOT a valid way to measure the reaction rate of the reaction below? $Cu(s) + 4H^+(aq) + 4NO_3^-(aq) \rightarrow Cu^{+2}(aq) + 2NO_3^-(aq) + 2NO_2(g) + 2H_2O(l)$
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In the reaction $2NO_{2(g)} \rightarrow 2NO_{(g)} + O_{2(g)}$, if during a 400s period the concentration of $NO_2$ changes from 0.100 M to 0.030 M, what is the reaction rate of $NO_2$?
In the reaction $2NO_{2(g)} \rightarrow 2NO_{(g)} + O_{2(g)}$, if during a 400s period the concentration of $NO_2$ changes from 0.100 M to 0.030 M, what is the reaction rate of $NO_2$?
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If a reaction shows a decrease in the concentration of a substance over time, is this species a reactant or a product?
If a reaction shows a decrease in the concentration of a substance over time, is this species a reactant or a product?
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If the rate of a reaction is reported as $-0.0033 M/s$, what does the negative sign indicate?
If the rate of a reaction is reported as $-0.0033 M/s$, what does the negative sign indicate?
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If Substance 'B' has an average reaction rate of +0.0033M/s, what does this suggest about the substance?
If Substance 'B' has an average reaction rate of +0.0033M/s, what does this suggest about the substance?
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Given an average reaction rate of -0.0033 M/s for substance A of a reaction, and a reaction time of 500s, what is the concentration change?
Given an average reaction rate of -0.0033 M/s for substance A of a reaction, and a reaction time of 500s, what is the concentration change?
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Study Notes
Reaction Rates and Data Analysis
- Reaction rate calculation (Nitrous Oxide): A 0.45M increase in nitrous oxide concentration over 3 minutes equates to a reaction rate of 0.0025M/s.
Reaction of Lithium and Nitrate Ions
- Reaction: Li⁺ + NO₃⁻ → LiNO₃
- Initial conditions: 5g lithium ions, 10g nitrate ions, 0g lithium nitrate
- 30 seconds later: 0g lithium ions, 5g nitrate ions, 5g lithium nitrate
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Reaction rates:
- Li⁺: -0.17g/s
- NO₃⁻: +0.17g/s
- LiNO₃: +0.17g/s
Measuring Reaction Rates
- Methods: Reaction rates can be measured by monitoring mass, concentration, or pressure changes.
Decomposition of NO₂
- Reaction: 2NO₂(g) → 2NO(g) + O₂(g)
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Data analysis (400s time period):
- NO₂: -0.000175M/s
- NO: +0.000175M/s
- O₂: +0.0000875M/s
Reaction of Reactant A to Product E
-
Data:
Time (min) Mass of A (g) 0 25.0 1.0 20.0 2.0 17.0 3.0 15.0 4.0 13.0 5.0 12.0 - Rate over 5 minutes: -2.6g/min
- Rate between 2 and 4 minutes: -2.0g/min
Average Reaction Rates for Substances A and B
- Data: Plotted concentration vs. time
- Species A: Reactant (concentration decreases)
- Species B: Product (concentration increases)
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Average rates:
- A: -0.0033 M/s
- B: +0.0033 M/s
Average Rates of Each Species (NO₂ and N₂O₄)
- Data: Concentration vs. time
- NO₂: +0.06M/s
- N₂O₄: -0.45M/s
Reaction Rate at 150s for Substances A and B
- Data from graph. Rates calculated by visual estimation.
Average Reaction Rates from 0-1200s
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Species:
- N₂O₅: -0.00021M/s
- NO₂: +0.00042M/s
- O₂: +0.00010M/s
Determining Reactants and Products
- NO₂: Product
- O₂: Product
- N₂O₅: Reactant
Rates of N₂O₅ Consumption and Product Formation
- NO₂ Formation rate: 4.8M/hr
- O₂ Formation rate: +1.2M/hr
Coefficients in the Rate Expression for NH₃
- Based on the reaction coefficients given
- Δ[NH₃] / Δt = -4 / 5 Δ[O₂] / Δt = -4/5 Δ[NO] / Δt = -4/5 Δ[H₂O]/Δt
Methane Combustion and Reaction Rates
- Reaction: CH₄ + 2O₂ → CO₂ + 2H₂O
- CH₄ Rate: -1.25 mol/s
- O₂ Rate: -2.5 mol/s
- H₂O Rate: +2.5 mol/s
- CO₂ Rate: +1.25 mol/s
Decomposition of Iron (III) Hydroxide
- Balanced equation: 2Fe(OH)₃ → Fe₂O₃ + 3H₂O
- Mass of Fe(OH)₃ required (1L, 0.096mol/L solution): 10.3g
- Rate of loss of Fe(OH)₃: -0.00172 M/s
Rates of Product Formation in Fe(OH)₃ Decomposition
- H₂O: +0.0026M/s
- Fe₂O₃: +0.00086M/s
Acetaldehyde Decomposition
- Balanced equation: CH₃CHO → CH₄ + CO
- Mass of CH₃CHO (1L, 0.00667M): 0.29g
- Rate of Acetaldehyde decomposition (42-105s): -0.000013M/s
Reaction Rates and Species Amounts in Chemical Reactions
- Analysis of changing amounts of species in various reactions
Factors Affecting Reaction Rates
- Concentration: Higher concentration leads to more collisions, increasing rate.
- Temperature: Higher temperature increases particle energy and collision frequency, increasing the rate.
- Volume: Decreasing volume leads to less space between particles, increasing collisions, but decreasing the rate.
- Catalysts: Catalysts lower activation energy, increasing the reaction rate.
- Pressure: Increasing pressure leads to more collisions, increasing rate.
- Surface Area: Larger surface area increases reaction sites, increasing rate.
Energy Diagrams and Reaction Rates
- Activation energy: Minimum energy needed for reaction to occur.
- Activated complex: Intermediate unstable state during a reaction
- Enthalpy change: Difference in energy levels between reactants and products
- Endothermic: Energy is absorbed by the reaction
- Exothermic: Energy is released from the reaction
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Description
Test your knowledge on reaction rates and data analysis in chemistry. This quiz covers calculations, measurements, and specific reactions involving various reactants. Prepare to dive into the details of how reaction rates are determined and analyzed.
