Sch4u: Unit Overview on Energy Changes and Chemical Reactions

SCH4U: UNIT OVERVIEW ON ENERGY CHANGES AND CHEMICAL REACTIONS

Submitted by: Amarinder Sawhney

Vanessa Poehlmann

Rajni Kant Sharma

UNIT DESCRIPTION / OVERALL EXPECTATIONS
This unit involves the study of thermodynamics, energy changes and Rates of reaction and factor affecting them. It involves study of potential energy diagrams for chemical reactions. Students will learn to solve the problems based on rates of reactions , energy changes, hess’s law / D1. analyse technologies and chemical processes that are based on energy changes, and evaluate them in terms of their efficiency and their effects on the environment;
D2. investigate and analyse energy changes and rates of reaction in physical and chemical processes, and solve related problems;
D3. demonstrate an understanding of energy changes and rates of reaction.
Specific expectations
D1 / D2 / D3
D1.1 analyse some conventional and alternative energy technologies (e.g., fossil fuel–burning power plants, hydro-powered generators, solar panels, wind turbines, fuel cells), and evaluate them in terms of their efficiency and impact on the environment [AI, C]
D1.2 analyse the conditions (e.g., temperature, pressure, presence of a catalyst) required to maximize the efficiency of some common natural or industrial chemical reactions (e.g., decomposition, combustion, neutralization),and explain how the improved efficiency of the reaction contributes to environmental sustainability [AI, C] / D2.1 use appropriate terminology related to energy changes and rates of reaction, including, but not limited to: enthalpy, activation energy, endothermic, exothermic, potential energy, and specific heat capacity [C]
D2.2 write thermo chemical equations, expressing the energy change as a ΔH value or as a heat term in the equation [AI, C]
D2.3 solve problems involving analysis of heat transfer in a chemical reaction, using the equation Q = m c ΔT(e.g., calculate the energy released in the combustion of an organic compound ,and express the results in energy per mole of fuel [J/mol]) [AI, C]
D2.4 plan and conduct an inquiry to calculate ,using a calorimeter, the heat of reaction of a substance (e.g., the heat of solution of ammonium nitrate, or of combustion of a hydrocarbon),compare the actual heat of reaction to the theoretical value, and suggest sources of experimental error [IP, PR, AI, C]
D2.5 solve problems related to energy changes in a chemical reaction, using Hess’s law [AI]
D2.6 conduct an inquiry to test Hess’s law (e.g., measure heats of reaction from the combustion
of magnesium, and combine them to yield the ΔH value of the reaction) [PR, AI]
D2.7 calculate the heat of reaction for a formation reaction, using a table of standard enthalpies of formation and applying Hess’s law [AI]
D2.8 plan and conduct an inquiry to determine how various factors (e.g., change in temperature, addition of a catalyst, increase in surface area of a solid reactant) affect the rate of a chemical reaction [IP, PR, AI] / D3.1 compare the energy changes resulting from physical change (e.g., boiling water), chemical reactions (e.g., bleaching a stain), and nuclear reactions (e.g., fission, fusion), in terms of whether energy is released or absorbed
D3.2 compare the energy change from a reaction in which bonds are formed to one in which bonds are broken, and explain these changes in terms of endothermic and exothermic reactions
D3.3 explain how mass, heat capacity, and change in temperature of a substance determine the amount of heat gained or lost by the substance
D3.4 state Hess’s law, and explain, using examples, how it is applied to find the enthalpy changes of a reaction
D3.5 explain, using collision theory and potential energy diagrams, how factors such as temperature ,the surface area of the reactants, the nature of the reactants, the addition of catalysts, and the concentration of the solution control the rate of a chemical reaction
D3.6 describe simple potential energy diagrams of chemical reactions (e.g., the relationships between the relative energies of reactants and products and the activation energy of the reaction)
D3.7 explain, with reference to a simple chemical reaction (e.g., combustion), how the rate of a reaction is determined by the series of elementary steps that make up the overall reaction mechanism
Content / Evaluation code / L= Learning strategies and A=assessment / E=Evaluation including criteria
1. Laws of thermodynamics, open system, closed system
[2 hrs]
Introduction of thermodynamics (heat reaction changes with closed and open vessel).
Explain the first law of thermodynamics by stating: “Energy cannot be created or destroyed it can only change forms.” Then explain the law of thermodynamics in open and close system by deriving the equation and with diagram
By the end of the lesson students will be able to ;
Differentiate between open and close system in terms of whether the energy is released or absorbed / D1, D1.1 D2, D2.1, D3 / L=Brain storming on open and closed system
A=Alternate- response / K/U
2.Enthalpy changes and heats of reaction
[3 hrs]
Introduction of key concepts related to heats of reactions pertinent to the lab activity such as: heats of reactions; calorimeters; specific heat capacity; and enthalpy. Explanation of definition of Enthalpy (H=E+PV) and describe change in enthalpy equation DH = H products – H reactants
After explaining thermo chemical equations derive its equations by expressing the energy change as a ΔH value or as a heat term in the equation [AI, C].
Solve numerical problems involving analysis of heat transfer in a chemical reaction, using the equation Q = m c ΔT (e.g., calculate the energy released in the combustion of an organic compound ,and express the results in energy per mole of fuel [J/mol]) [AI, C]
By the end of the lesson students will be able to calculate;
Better understand the heat flow between reactant and product
Heat of reaction for a formation reaction, using a table of standard enthalpies of formation.
Heat of a reaction using a calorimeter, and use that data obtained to calculate the enthalpy change for a reaction.
Solve numerical problems related to thermo chemical equation. / D2, D3,D2.2, D2.3, D2.7 / L= Start with a think-pair-share question regarding enthalpy as an energy change in a reaction
L = Lecture , demonstration , discussion
A= Numerical problems / K/U , C
3. Calorimetry Lab: The heat of solution of ammonium nitrate.
[1 hr]
Demonstrate an experiment in the lab using solution of ammonium nitrate NH4No3
By the end of the lesson students will be able to ;
Compare the actual heat of reaction to the theoretical value / D2, D2.4 / L=Classroom Laboratory (Link “Lab 3” at end of document, the solid is not indicated in the lab procedure, but ammonium nitrate should be used).
A=Completed laboratory report from link, including “Advance Study Assignment” page 4-5. One question to be added – Propose possible sources of error. / E = Level 1-4 rubric attached to laboratory.
Assessing all 4 categories: K/U, A, T/I, C.
4. Hess’s law
[3 hrs]
Explain principle of Hess’s law and how it is applied to find the enthalpy changes of a reaction by giving examples of oxidation of nitrogen to produce nitrogen dioxide.
N2 (g) +2O2 (g) --- 2NO2 (g)
Where DH = 68 KJ
Solve numerical problems related to energy changes in a chemical reaction, using Hess’s law.
Explain Hess’s law using real life examples like fire walking.
By the end of the lesson students will be able to ;
Calculate change in enthalpy (DH) of a chemical reaction.
Understand characteristics of enthalpy
Able to distinguish endothermic and exothermic reaction.
Better understand the heat flow between reactant and product
How to use Hess law in solving numerical problem / D2, D3, D3.4 / L= Lecture, problem solving, discussion
A= Numerical problem / E= numerical problem
E1=excellent, A= good, B= fair, C= not understood
5. Testing Hess’s Law
[1hr]
Online Java Simulation. Measure heats of reaction from the combustion of magnesium, and combine them to yield the ΔH value of the reaction. / D2.6 / L = Online Simulation (See “Lab 5” link at end of document),
A = Completed enthalpy diagram and ΔH value of the reaction. / E = Level 1-4 rubric attached to laboratory.
Assessing A & T/I.
6. Problems on enthalpy, Gibbs free energy, entropy
[3hrs]
Solve numerical problems based on enthalpy
Explain and derive the equation based on gibbs free energy and then solve problems involving the Gibbs equation, ΔG = ΔH – TΔS
By the end of the lesson students will be;
Able to explain relation between Gibbs free energy, entropy and enthalpy and would be able to solve problems based on it. / D2, D2.7, D3.3 / L= Problem solving, question and answer
A= Numerical problem / E= Objective test,
E1=excellent, A= good, B= fair, C= not understood
7.Rates of reaction
[2 hrs]
Describe rate of reaction which states that, “how quicklyreactants are used upor how quicklyproducts are formedduring a chemical reaction.” The units used are: (moles/second)
Factor effecting rates of reaction and explain endothermic and exothermic reaction.
By the end of the lesson students will be;
Measuring rate of reaction in the lab / D3, D3.2 / L= Lecture, experimentation, demonstration
A= Short essay
8. Potential energy diagrams and collision theory
By the end of the lesson, students will be able to describe simple potential energy diagrams of chemical reactions, including relationships between the relative energies of reactants and products and the activation energy of the reaction. Also students can explain collision theory and its relationship to chemical reactions.
[2 hrs] / D3.5, D3.6 / L= Lecture & class discussion on potential energy diagrams. Student activity on collision theory: Molecule speed dating! How do molecules meet and interact, an interactive simulation of collision theory on the macro level.
A= Draw potential energy diagrams, labeled with calculations. / E = Marking scheme for potential energy diagrams.
Assessing KU and C in potential energy diagrams, and I/T for simulation of collision theory.
9. Collision Theory Gizmo
[2 hrs]
Online simulation to determine how various factors (e.g., change in temperature, addition of a catalyst, increase in surface area of a solid reactant) affect the rate of a chemical reaction / D2.8, D3.5 / L=Online Gizmo Simulation (Link “Lab 9” at end of document).
A=Completed Student Exploration Guide from website. Note: This is a long Gizmo. Prior Knowledge Questions can be discussed in previous lesson, but Gizmo is allotted 2 periods for completion. / E = Level 1-4 rubric attached to student exploration guide.
Assessing K/U & C.
10. Controlled reactions
By the end of the lesson, student will be able to explain, with reference to a simple chemical reaction (e.g., combustion), how the rate of a reaction is determined by the series of elementary steps that make up the overall reaction mechanism.
[1 hr] / D3.7 / L= Graffiti Wall: students walk around to stations with poster paper and circle intermediates in a series of chemical equations. In the final rotation students write the overall chemical reaction. Completed with class discussion on the importance of intermediates and how they help us find the rate of reaction.
A= Students post their corrected poster papers from the Graffiti Walk. / Assessing A, C & T/I.
11. Unit Test Review / All expectations / Prepared multiple-choice clicker presentation. Clicker questions should take 20-25 mins, followed by students working in pairs to focus on incorrect answers. / E = report from clicker software on incorrect answers.
12. Unit Test

Lab 3: http://sunny.moorparkcollege.edu/~chemistry/chemistry_1B_labs/experiment_one.pdf

Lab 5: http://www.dartmouth.edu/~chemlab/info/resources/deltah/deltah.html

Lab 9: http://www.explorelearning.com/index.cfm?method=cResource.dspView&ResourceID=553

Accommodations for (ELL) English language learners

v  Access to dictionary

v  Use visuals/ manipulative

v  Teach key vocabulary

v  Adjust speech

v  Utilize cooperative learning methods

v  Use coping strategies

v  Give them extra time

v  Make activities more simple

v  Provide native language instruction and materials

v  Provide “think aloud” and modeling

v  Set language, content, and learning-strategy objectives

v  Tap students’ prior knowledge.

v  Scaffolding of tasks

Accommodations for students with IEPs

v  Increase the variety of information available

v  Use assignments according to student readiness

v  Do not explore related ethical issues

v  Give them extra time

v  Tap students’ prior knowledge

v  Utilize cooperative learning methods

v  Use coping strategies

v  Scaffolding of tasks

v  Give them extra time

v  Access to dictionary

v  Be sympathetic and accommodating to his needs.

v  Make activities more simple

v  Accelerate activities from concrete to abstract, move slowly

v  Modify outcomes from a lower grade level

v  Do not extend activities beyond the regular program of studies

v  For laboratories keep groups consistent to avoid stress caused by change

REFERENCES:

Ontario curriculum for senior science

http://schools.hwdsb.on.ca/westdale/files/2010/10/Grades-11-and-1210.pdf

Growing success- Assessment, Evaluation, and Reporting in Ontario schools

http://www.edu.gov.on.ca/eng/policyfunding/growSuccess.pdf

Culminating Task

SCH4U Strand D: Energy Changes and Rates of Reactions

(Submitted by Vanessa Poehlmann, Amarinder Sawhney, Rajni Kant Sharma)

Background Information

The foundation of the study of thermochemistry is Hess’s Law which states :

The enthalpy change for any reaction depends on the products and the reactants and is independent of the pathway or the number of steps between the reactant and product.

This task is divided into two parts

Part A tests students KIU part of assessment tools and Part B tests A part of evaluation tools.

Part A is group task involving 2 or 3 students in one group and Part B is individual task.

Part A Energy changes- Applications of Hess’s law in lab

In this experiment, you will measure and compare the quantity of heat involved in the following three reactions. Half of class will choose reaction 1 and other half will choose reaction 2. Reaction 3 will be performed by every group. Students will share readings of 1 and 2 and will solve equation3

Neutralisation reaction between HCl and NaOH

1. The dissolving of solid sodium hydroxide in water:

NaOH(s) Na+(aq) + OH-(aq) + heat