Topic Enthalpy changes and Level energy level diagrams

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Topic Enthalpy changes and Level energy level diagrams Outcomes 1. To understand the terms

Topic Enthalpy changes and Level energy level diagrams Outcomes 1. To understand the terms exothermic and endothermic 2. To be able to draw energy level diagrams for endothermic and exothermic reactions Information • for teachers GCSE (or any course for students aged 14 -16) These slides take students through a series of steps to help understand energy level diagrams for exothermic and endothermic reaction. You could use these slides once students have been taught the basics. Students will initially struggle to understand why an exothermic reactions has a negative enthalpy change. www. thescienceteacher. co. uk | resources for science teachers who like to think

The men in this picture are being kept warm by the fire. We can

The men in this picture are being kept warm by the fire. We can use a diagram to show what energy changes are taking place when the wood burns.

Energy (J) Questions Where are the products on this energy level diagram? ΔH =

Energy (J) Questions Where are the products on this energy level diagram? ΔH = positive or negative? ΔT(surroundings) = positive or negative? reactants (fuel + oxygen) Progress of reaction

Temperature of surroundings would increase. Energy (J) reactants (fuel + oxygen) ΔH = negative

Temperature of surroundings would increase. Energy (J) reactants (fuel + oxygen) ΔH = negative products (carbon dioxide + water) Progress of reaction

Questions Energy (J) ΔH = positive or negative? ΔT(surroundings) = positive or negative? Reactants

Questions Energy (J) ΔH = positive or negative? ΔT(surroundings) = positive or negative? Reactants Products Progress of reaction

Questions ΔH = positive or negative? ΔT(surroundings) = positive or negative? Energy (J) Products

Questions ΔH = positive or negative? ΔT(surroundings) = positive or negative? Energy (J) Products Reactants Progress of reaction

Questions Energy (J) ΔH = positive or negative? ΔT(surroundings) = positive or negative? Reactants

Questions Energy (J) ΔH = positive or negative? ΔT(surroundings) = positive or negative? Reactants Products Progress of reaction

Questions ΔH = positive or negative? ΔT(surroundings) = positive or negative? Energy (J) Products

Questions ΔH = positive or negative? ΔT(surroundings) = positive or negative? Energy (J) Products Reactants Progress of reaction

Before the reaction could begin, the man had to light the fire with a

Before the reaction could begin, the man had to light the fire with a match. Can you show this on your energy level diagram? We call the minimum energy needed to start a reaction the activation energy or Ea.

Ea Energy (J) Reactants (fuel + oxygen) ΔH Products (carbon dioxide + water) Progress

Ea Energy (J) Reactants (fuel + oxygen) ΔH Products (carbon dioxide + water) Progress of reaction

Which colour line represents the enthalpy change? Energy (J) Which colour line represents the

Which colour line represents the enthalpy change? Energy (J) Which colour line represents the activation energy? Progress of reaction

Which colour line represents the enthalpy change? Energy (J) Which colour line represents the

Which colour line represents the enthalpy change? Energy (J) Which colour line represents the activation energy? Ea Progress of reaction

Sketch your own energy level diagrams 1. A reaction with a small activation energy

Sketch your own energy level diagrams 1. A reaction with a small activation energy where ΔH is negative 2. An enothermic reaction with a large activation energy 3. The reaction between Mg and O 2 4. The combustion of petrol 5. The reaction inside an ice pack 6. Melting snow

Think deep! If a match is required to start a fire, why doesn’t the

Think deep! If a match is required to start a fire, why doesn’t the fire go out when the match finishes burning? Ea Energy (J) reactants (fuel + oxygen) ΔH products (carbon dioxide + water) Progress of reaction

ENTHALPY CHANGES ENTHALPY CHANGES CONTENTS Thermodynamics Enthalpy changesENTHALPY CHANGES ENTHALPY CHANGES CONTENTS Thermodynamics Enthalpy changes
Enthalpy ENTHALPY CHANGES ENTHALPY H the energy contentEnthalpy ENTHALPY CHANGES ENTHALPY H the energy content
Topic Enthalpy changes and Level energy level diagramsTopic Enthalpy changes and Level energy level diagrams
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Enthalpy Enthalpy Enthalpy His the total amount ofEnthalpy Enthalpy Enthalpy His the total amount of
ENTHALPY CHANGES ENTHALPY A guide for A levelENTHALPY CHANGES ENTHALPY A guide for A level
CALORIMETRY ENTHALPY CHANGES be able to define enthalpyCALORIMETRY ENTHALPY CHANGES be able to define enthalpy
CALORIMETRY ENTHALPY CHANGES be able to define enthalpyCALORIMETRY ENTHALPY CHANGES be able to define enthalpy
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Energy Unit 7 Enthalpy PE diagrams Phase ChangesEnergy Unit 7 Enthalpy PE diagrams Phase Changes
Chemistry Energy Revision Contents Enthalpy First Law EnthalpyChemistry Energy Revision Contents Enthalpy First Law Enthalpy
ENTHALPY CHAPTER ELEVEN TYPES OF ENTHALPY Thermal energyENTHALPY CHAPTER ELEVEN TYPES OF ENTHALPY Thermal energy
Enthalpy Calculations And the specific heat equation EnthalpyEnthalpy Calculations And the specific heat equation Enthalpy