Phase Shifts Slides Atomic Alchemy • Unit 1
Session 26-27
Phase Shifts
Investigating states of matter, molecular arrangements, and the invisible bonds that hold our universe together.
TOPIC 1.1 States & IMFs
TOPIC 1.2 Energy & Phase Changes
Slide 1 of 4
Microscopic Behavior
Atomic Alchemy
Solids
Definite shape & volume
Particles vibrate in fixed lattices. Strong IMFs
Liquids
Indefinite shape, definite volume
Particles slide past each other. Moderate IMFs
Gases
Indefinite shape & volume
Particles in constant rapid motion. Weak / Negligible IMFs
Focus: Note physical shifts and intermolecular transitions.
Slide 2 of 4
Energy Direction
Atomic Alchemy
Endothermic Processes
System ABSORBS thermal energy from surroundings
MELTING → Solid to Liquid (Breaking tight lattice)
BOILING → Liquid to Gas (Overcoming all IMFs)
SUBLIME → Solid directly to Gas (e.g., Dry Ice)
Exothermic Processes
System RELEASES thermal energy to surroundings
FREEZING → Liquid to Solid (Creating fixed lattices)
CONDENSE → Gas to Liquid (Establishing IMFs)
DEPOSIT → Gas directly to Solid (e.g., Frost)
Crucial rule: Endothermic +Heat, Exothermic -Heat.
Slide 3 of 4
Formative Check
Atomic Alchemy
What happens to heat when water evaporates from your skin?
Think about why your body cools down. Is the water absorbing energy from you, or releasing it to you?
1
Identify the system (water) and the surroundings (skin).
2
Decide if energy moves IN to break liquid IMFs (endo) or moves OUT (exo).
Class Prompt
Discuss with a peer: Draw a microscopic diagram of ice turning to steam. How does kinetic energy change?
Did You Know?
Steam at 100°C causes much more severe burns than liquid water at 100°C. This is due to the latent heat of vaporization!
Get ready to fill out your Molecular Shifter log sheets!
Slide 4 of 4
Phase Shifts Worksheet Atomic Alchemy • Unit 1
Phase Shifts Worksheet
Document ID: ALCH-1.01
Ver: 2026-2027
STUDENT NAME: ___________________________
DATE: ___________________________
Instructions
Complete each particulate diagram and answer the conceptual questions. Ensure your diagrams clearly reflect the spacing, organization, and intermolecular attractions of the particles.
1 Particulate Arrangements
In the boxes below, draw exactly 8 particles of substance X to illustrate each phase. Use simple circles. Keep the background clean.
SOLID STATE
Describe IMF Strength
LIQUID STATE
Describe Molecular Motion
GASEOUS STATE
Describe Container Volume Fill
2 Terminology Match
1. Direct Solid to Gas transformation
2. Internal IMF energy holding liquid structure
A. Sublimation
B. Intermolecular Forces
Unit 1: Molecular Shifters
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Atomic Alchemy • Unit 1
Phase Shifts Worksheet
Document ID: ALCH-1.01
Ver: 2026-2027
3 Thermodynamic Directions
Identify each process as either Endothermic (absorbs heat) or Exothermic (releases heat) .
1. Dew forming on grass on a cool morning
Water vapor in the air transitions to liquid droplets on leaves.
ENDOTHERMIC EXOTHERMIC
2. Dry ice (solid carbon dioxide) smoking at room temperature
Solid carbon dioxide changes directly to carbon dioxide gas.
ENDOTHERMIC EXOTHERMIC
3. Liquid lava solidifying into rock after an eruption
Molten silicate minerals cool and recrystallize into basalt rock.
ENDOTHERMIC EXOTHERMIC
4 Critical Thinking: Latent Heat
Explain why the temperature of boiling water remains constant at exactly 100°C, even though thermal energy is constantly added to the beaker. Refer to intermolecular forces and kinetic energy .
Unit 1: Molecular Shifters
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Phase Shifts Teacher Guide Atomic Alchemy • Unit 1
Phase Shifts Teacher Guide
TEACHER COMPANION
Pacing: 55 Minutes
Focus: Phase Thermodynamics
Subject: High School Chem
Lesson Goals
Analyze matter arrangements at the microscopic particulate scale for solids, liquids, and gases.Differentiate between endothermic and exothermic phase changes at structural and thermal levels.Explain latent heat and temperature plateau during phase transitions in terms of intermolecular bonds.
Suggested Pacing Guide
Section Time Details 1. Mini-Lecture 15 min Use Phase Shifts Slides to present solids, liquids, gases, and IMFs. 2. Guided Draw 15 min Students draft particulate models on Page 1 of the Worksheet. 3. Scenario Analysis 15 min Solve thermodynamics questions; peer discussions. 4. Wrap-up & Check 10 min Clarify latent heat concepts and review answers.
Master Answer Key
Part 1: Particulate Arrangements Guidance
Solid: 8 particles packed tightly in an orderly crystalline lattice. Forces = Maximum.Liquid: 8 particles closely grouped but unordered, resting at the bottom of the container space.Gas: 8 particles widely spaced, filling all upper corners. Forces = Negligible.
Part 2 Match Answers
1. Direct Solid to Gas = A (Sublimation)
2. Bond forces holding structure = B (Intermolecular Forces)
Part 3 Scenario Answers
1. Dew Forming = Exothermic
2. Dry Ice = Endothermic
3. Lava Solidifying = Exothermic
Part 4: Latent Heat Rubric
Full Credit (3 pts): Explains that added thermal energy does not raise kinetic energy (temperature) during a phase change; instead, it is consumed to break/overcome intermolecular forces between liquid molecules.
Unit 1: Molecular Shifters
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Matter Energy Portfolio IISD 26-27 Chemistry • Investigation 1
Matter, Energy, and Change
Log ID: ME-EXP-01
Experience 1 Portfolio
NAME: ______________
DATE: ______________
CLASS: _____________
TIME (T)
55 Minutes Total
VOICE LEVEL (V)
Level 1 (Whisper Mode)
BODY (B)
Writing actively, at desk
1. ENGAGE Keep a Fire Burning
Observe the candle demonstration. Check off the three components required for active combustion:
Fuel Source Oxygen (\(O_2\)) Heat Energy
2. EXPLORE Lab: Measuring the Energy in a Dorito
Record your calorimeter measurements below. Use the heat absorption formula to analyze energy transfer.
Measurement Parameter Recorded Trial Value Mass of Snack Chip (Initial) ________________________ g Volume of Calorimeter Water ________________________ mL Initial Temperature (\(T_i\)) ________________________ °C Final Temperature (\(T_f\)) ________________________ °C
3. EXPLAIN & ELABORATE Wildfires & 1st Law
How does the burning of forest wood illustrate the First Law of Thermodynamics ? Write an argument below containing your claim, evidence, and reasoning.
CLAIM:
EVIDENCE:
REASONING:
Experience 1 • Matter & Energy
⏱️ 🗣️ 👤 TVB ACTIVE
Page 1 of 4
IISD 26-27 Chemistry • Investigation 1
Matter, Energy, and Change
Log ID: ME-EXP-02
Experience 2 Portfolio
NAME: ______________
DATE: ______________
CLASS: _____________
TIME (T)
45 Minutes Total
VOICE LEVEL (V)
Level 2 (Peer Discuss)
BODY (B)
Standing in groups, wearing goggles
1. EXPLORE Lab: Energy Flow in Chemical Reactions
React Calcium Oxide (\(CaO\)) with water in a sealed zipper bag. Record physical observations:
Temperature Log:
Initial Temp: _______________ °C
Maximum Temp: _______________ °C
Change (\(\Delta T\)): _______________ °C
Tactile Observations:
2. EXPLAIN Microscopic Particle Velocity Models
Bond Breakers Slides Atomic Alchemy • Unit 2
Session 26-27
Bond Breakers
Differentiating between physical transformations and chemical rearrangements at both macro and micro levels.
TOPIC 2.1 Physical Changes
TOPIC 2.2 Chemical Changes
Slide 1 of 4
Physical Transformations
Atomic Alchemy
Altering Form, Not Identity
Physical changes only modify the physical state, shape, size, or appearance of a substance. No intramolecular bonds are broken.
Key Examples
Phase Transitions
Shaping / Tearing
Making Mixtures
Dissolving Salts
Particulate View of Melting Water
Ice (Solid)
→
Water (Liquid)
The molecules \(H_2O\) remain intact. No atomic bonds are altered.
Notice that the individual compounds look exactly the same before and after!
Slide 2 of 4
Chemical Rearrangements
Atomic Alchemy
Macroscopic Clues
How do we spot chemical reactions happening in real time? Watch for these five major laboratory signs:
Heat/Light Output
Gas Produced (Bubbles)
Precipitate Forms
Unexpected Color Shift
Particulate View of Hydrogen Combustion
Reactants (\(H_2 + O_2\))
→
Products (\(H_2O\))
New substances are formed! Original covalent bonds are broken, and brand-new bonds are synthesized.
Remember: Intermolecular forces break during physical shifts; Intramolecular bonds break during chemical reactions.
Slide 3 of 4
Interactive Check
Atomic Alchemy
Is dissolving sugar in hot water a chemical or physical change?
Many students struggle here! If the sugar crystals "disappear", does that mean its chemical structure has completely changed?
A
Physical: Water separates the sugar molecules but does not break the individual sugar rings apart.
B
Chemical: New solution forms and can never be reversed.
The Verdict
It is a PHYSICAL change! You can evaporate the water to completely retrieve the solid sugar crystals unchanged.
Think Like a Chemist
To prove a chemical shift occurred, you must find evidence of a new compound with entirely unique chemical properties.
Get ready to use indicators of change during today's laboratory investigations!
Bond Breakers Worksheet Atomic Alchemy • Unit 2
Bond Breakers Worksheet
Document ID: ALCH-2.01
Ver: 2026-2027
STUDENT NAME: ___________________________
DATE: ___________________________
Macroscopic vs Microscopic Rules
Physical changes change state or layout but do not create new compounds. Chemical changes break intramolecular bonds, rearrange atoms, and create brand-new substances with unique properties.
1 Categorizing Physical and Chemical Changes
Classify each real-world process. Under "Primary Clue", write which of the 5 indicators (or lack thereof) guided your choice.
Scenario Description Classification Primary Clue / Indicator A tablet of Alka-Seltzer dropped into warm water begins fizzing and releasing bubbles. [ ] Physical [ ] Chemical _________________ An iron nail left outside in damp weather develops a crumbly orange-brown coating. [ ] Physical [ ] Chemical _________________ Liquid rubbing alcohol poured on a countertop evaporates rapidly, leaving behind no residue. [ ] Physical [ ] Chemical _________________ Clear hydrochloric acid is added to clear sodium hydroxide, and the flask gets hot to the touch. [ ] Physical [ ] Chemical _________________
Unit 2: Bond Breakers
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Atomic Alchemy • Unit 2
Bond Breakers Worksheet
Document ID: ALCH-2.01
Ver: 2026-2027
2 Microscopic Rearrangements
The reaction between Hydrogen (\(H_2\)) and Chlorine (\(Cl_2\)) produces Hydrogen Chloride gas (\(HCl\)). In the boxes below, draw the microscopic view of this reaction. Use shaded circles (\(\bullet\)) for Chlorine and open circles (\(\circ\)) for Hydrogen.
REACTANTS (4 \(H_2\) and 4 \(Cl_2\) molecules)
Draw as diatomic molecular pairs
PRODUCTS (8 \(HCl\) molecules)
Draw as bonded pairs of open + shaded circles
3 Micro-level Explanation
At the atomic level, how does the behavior of atoms during a physical change differ from their behavior during a chemical change ? Use terms like intermolecular forces , covalent bonds , and rearrangement .
Unit 2: Bond Breakers
Bond Breakers Teacher Guide Atomic Alchemy • Unit 2
Bond Breakers Teacher Guide
TEACHER COMPANION
Pacing: 60 Minutes
Focus: Macroscopic vs Microscopic
Subject: High School Chem
Lesson Goals
Identify the five macroscopic indicators of a chemical reaction.Contrast intramolecular bond breaking (chemical) with intermolecular force disruption (physical).Draw accurate reactant and product particle arrangements to demonstrate mass conservation and chemical rearrangement.
Recommended Classroom Demonstrations
Demo A: Steel Wool in Vinegar (Chemical)
Demo B: Water + Ethanol Mixing (Physical)
Worksheet Answer Key
Part 1: Macroscopic Scenarios Key
Alka-Seltzer: Chemical. Clue: Gas production (vigorous bubbling).Iron Nail Rusting: Chemical. Clue: Unexpected color change (orange-brown) & new precipitate layer.Alcohol Evaporating: Physical. Clue: No indicators; phase transition from liquid to gas.Acid + Base Mixing: Chemical. Clue: Temperature shift (exothermic reaction releasing heat).
Part 2: Drawing Guide
Reactants: Should feature 4 separate diatomic pairs of open circles (\(\circ\text{-}\circ\)) and 4 separate pairs of shaded circles (\(\bullet\text{-}\bullet\)).
Products: Should feature 8 separate bonded pairs containing one open and one shaded circle (\(\circ\text{-}\bullet\)).
Part 3: Explanations Key
Students must explain that in physical shifts , molecules move relative to each other but covalent bonds remain intact. In chemical changes , intramolecular covalent bonds break, atoms reorganize, and new compounds are built.
Unit 2: Bond Breakers
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Mass Keepers Slides Atomic Alchemy • Unit 3
Session 26-27
Mass Keepers
Mastering the Law of Conservation of Mass, counting atomic ratios, and balancing chemical equations like a pro.
TOPIC 3.1 Conservation Law
TOPIC 3.2 Balancing Equations
Slide 1 of 4
The Conservation Law
Atomic Alchemy
Matter is Eternal
The Law of Conservation of Mass states that mass in an isolated system can neither be created nor destroyed by chemical reactions or physical transformations.
Key Equation Rules
Number of reactant atoms of each element MUST EQUAL the number of product atoms of each element.
Balanced Scales of Chemistry
REACTANTS
100g total
[Carbon + Oxygen]
PRODUCTS
100g total
[Carbon Dioxide]
No matter how explosive or dramatic the chemical transition, not a single atom is lost.
If gas escapes an open beaker, the mass may seem to decrease, but it is just floating in the room!
Slide 2 of 4
Balancing Pro-Tips
Atomic Alchemy
The Two Rules of Balancing
Rule #1
Adjust only Coefficients
Add large numbers in front of compounds (\(\mathbf{2} H_2O\)). Never change subscripts (\(H_2O_{\mathbf{3}}\)), as that changes the chemical identity!
Rule #2
Keep an Inventory
Construct an element table below the reaction arrow and update counts systematically until both sides match.
Equation In Practice
\(\mathbf{2} H_2 + O_2 \rightarrow \mathbf{2} H_2O\)
REACTANT SIDE 4 Hydrogen
VS
PRODUCT SIDE 4 Hydrogen
Multiplying a coefficient scales the entire molecule.
Tip: Always balance lone elements (like isolated metals or pure \(O_2\)) last!
Slide 3 of 4
Equation Showdown
Atomic Alchemy
Balance the combustion of methane gas in your logs:
\(\underline{\text{ }} CH_4 + \underline{\text{ }} O_2 \rightarrow \underline{\text{ }} CO_2 + \underline{\text{ }} H_2O\)
Let's count: Reactants have 4 Hydrogen atoms. How many does the product side currently have? What coefficient fits in front of water?
Step-by-step guidance
Check Carbon first: 1 on left, 1 on right. (Balanced!)
Mass Keepers Worksheet Atomic Alchemy • Unit 3
Mass Keepers Worksheet
Document ID: ALCH-3.01
Ver: 2026-2027
STUDENT NAME: ___________________________
DATE: ___________________________
How to Balance
Fill in the coefficient spaces with small whole integers. If a coefficient is a "1", write "1" in the space (do not leave blank). Make sure to count the total atoms for each element on reactants and products!
1 Balancing Chemical Reactions
Add coefficients to balance each reaction. Beneath each equation, list your final atom inventory counts.
A. \(N_2\) + \(H_2\) \(\rightarrow\) \(NH_3\)
Reactants: N = ____ , H = ____
Products: N = ____ , H = ____
B. \(Al\) + \(O_2\) \(\rightarrow\) \(Al_2O_3\)
Reactants: Al = ____ , O = ____
Products: Al = ____ , O = ____
Unit 3: Mass Keepers
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Atomic Alchemy • Unit 3
Mass Keepers Worksheet
Document ID: ALCH-3.01
Ver: 2026-2027
2 The Escaping Gas Paradox
A chemist reacts exactly 10.0g of Baking Soda with 20.0g of Vinegar inside a beaker. When mixed, bubbles of Carbon Dioxide gas fly out. The final mass of liquid in the beaker is measured at 27.5g .
A. What mass of \(CO_2\) gas escaped?
Show your subtraction calculation in the workspace below:
B. Open vs. Closed System
How would the final mass read on the scale differ if the beaker was sealed with a rubber stopper?
3 Subscript Conceptual Challenge
A fellow student says: "To balance the combustion of hydrogen (\(H_2 + O_2 \rightarrow H_2O\)), we can just change the water product formula to \(H_2O_2\) to match the oxygen atoms on the reactant side." Explain why this is an invalid scientific approach . Refer to the difference between coefficients and subscripts.
Unit 3: Mass Keepers
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Mass Keepers Teacher Guide Atomic Alchemy • Unit 3
Mass Keepers Teacher Guide
TEACHER COMPANION
Pacing: 60 Minutes
Focus: Equations & Conservation
Subject: High School Chem
Lesson Goals
Apply the Law of Conservation of Mass to determine mass changes in chemical reactions.Balance chemical equations using correct small whole number stoichiometric coefficients.Explain why changing subscripts is mathematically and chemically invalid.
Common Student Pitfalls
Subscript Tampering: Students frequently change subscripts (e.g., changing \(H_2O\) to \(H_2O_2\) to balance oxygens) because it feels simpler. Emphasize that \(H_2O\) is vital for life, while \(H_2O_2\) is a skin bleach and toxic disinfectant. Chemical formulas define substance identity!
Forgotten Gaseous Mass: When reactions lose mass, students assume matter was "destroyed". Force them to trace where gas bubbles go and model closed flasks to prove total conservation.
Worksheet Answer Key
Part 1: Equation Solutions
A. Nitrogen + Hydrogen:
\(\mathbf{1} N_2 + \mathbf{3} H_2 \rightarrow \mathbf{2} NH_3\)
Reactant / Product inventory: N = 2, H = 6
B. Aluminum + Oxygen:
\(\mathbf{4} Al + \mathbf{3} O_2 \rightarrow \mathbf{2} Al_2O_3\)
Reactant / Product inventory: Al = 4, O = 6
Part 2: Conservation Solutions
A. Gas Mass Calculation:
B. Sealed Beaker: 30.0g because gas cannot leave.
Part 3: Concept Key
Changing subscripts changes the chemical compound. \(H_2O_2\) is hydrogen peroxide, which has radically different molecular properties than water. To conserve mass, we must only scale the number of intact molecules using coefficients .
Unit 3: Mass Keepers
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Heat Hunters Slides Atomic Alchemy • Unit 4
Session 26-27
Heat Hunters
Tracking chemical enthalpy, interpreting reaction diagrams, and decoding the energy flow in heating curves.
TOPIC 4.1 Enthalpy & Diagrams
TOPIC 4.2 Heating Curves
Slide 1 of 4
Energy Coordinate Diagrams
Atomic Alchemy
Measuring Chemical Enthalpy (\(\Delta H\))
Enthalpy represents the total heat content of a chemical system. The net energy shift during a reaction is designated as \(\Delta H = H_{\text{products}} - H_{\text{reactants}}\).
Endothermic
\(\Delta H > 0\). Heat enters system. Surroundings get cold.
Exothermic
\(\Delta H < 0\). Heat leaves system. Surroundings get hot.
Exothermic reaction coordinate
High Energy Low Energy
Reactants
Products
-\(\Delta H\) (Released)
Product energy is lower than reactant energy. The excess difference is emitted as thermal heat.
Notice the activation energy hump that must be scaled before reactants can yield products!
Slide 2 of 4
Heating Curve Dynamics
Atomic Alchemy
Decoding the Heating Curve
When heat is steadily added to ice, temperature behaves unexpectedly. Let's study the flat plateaus:
Sloped Regions: Heat increases particle kinetic energy. Temperature rises inside the single state of matter (solid, liquid, or gas).
Flat Plateaus: Heat is used entirely to disrupt and overcome intermolecular forces. Temperature remains flat.
Water Heating Curve Diagram
Temp (°C)
Heat Added
Solid
Melting
Liquid
Boiling
The boiling plateau is longer than the melting plateau because vaporizing liquid requires breaking all remaining IMFs!
Did you know? Latent heat of vaporization for water is 2260 J/g, while fusion is only 334 J/g!
Slide 3 of 4
Unit Synthesis Challenge
Atomic Alchemy
How do we connect all four Atomic Alchemy lessons?
From particle layouts and physical/chemical bond breaking, to scaling reactions in balanced equations, everything is governed by energy flow!
Final Quiz Core Concepts
Review states and IMF attractions.
Define macroscopic chemical change indicators.
Solve chemical mass conservation models.
Heat Hunters Worksheet Atomic Alchemy • Unit 4
Heat Hunters Worksheet
Document ID: ALCH-4.01
Ver: 2026-2027
STUDENT NAME: ___________________________
DATE: ___________________________
Thermodynamics Rules
Enthalpy change (\(\Delta H\)) is products minus reactants. Exothermic reactions release heat and have a negative \(\Delta H\). Endothermic reactions absorb heat and have a positive \(\Delta H\).
1 Analyzing Reaction Diagrams
Study the reaction diagram below, then answer the questions based on its coordinate path.
Reactants (50 kJ) Transition State (150 kJ) Products (100 kJ)
Reaction Progress
A. What is the energy of the reactants? Answer: _______________________ kJ
B. What is the energy of the products? Answer: _______________________ kJ
C. Calculate the Enthalpy Change (\(\Delta H\)): Calculation: ____________________ kJ
D. Is this reaction Endothermic or Exothermic? Answer: _______________________
Unit 4: Heat Hunters
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Atomic Alchemy • Unit 4
Heat Hunters Worksheet
Document ID: ALCH-4.01
Ver: 2026-2027
2 Water Heating Curve
Below is a standard water heating curve starting at -20°C and rising to 120°C. Identify each labeled interval.
Interval A Interval B Interval C Interval D Interval E
Identify States / Phase changes
Interval A: ____________________________
Interval B: ____________________________
Interval C: ____________________________
Interval D: ____________________________
Interval E: ____________________________
Plateau Reasoning
Why does Interval D require significantly more added energy (represented by horizontal length) than Interval B?
3 Micro-Energy Synthesis
Explain what is happening to the kinetic energy of water molecules during Interval C compared to Interval B .
Unit 4: Heat Hunters
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Heat Hunters Unit Exam Atomic Alchemy • Cumulative Assessment
Unit Exam: Molecular Shifters
Document ID: EXAM-1.00
Points: 50 Total
STUDENT NAME: ___________________________
DATE: ___________________________
1 Multiple Choice (15 Points)
1. Which phase change represents an EXOTHERMIC process?
A. Liquid water boiling into steam B. Dry ice sublimating directly into gas C. Water vapor condensing on grass D. Ice melting on a kitchen counter
2. If 15.0 grams of copper completely reacts with chlorine gas in a sealed tube, what must be true of the final product mass?
A. Product mass will equal exactly 15.0 grams B. Product mass will be greater than the copper mass but equal copper + chlorine C. Product mass will be less than 15.0 grams because chlorine is a light gas
3. Why is the temperature during a boiling plateau constant?
A. Added energy is spent breaking intermolecular forces rather than raising kinetic energy B. Added energy is converted directly into atomic mass inside molecules
2 Balancing Equations (15 Points)
Balance the chemical equation below. Draw the atom inventory to prove conservation.
\(Fe\) + \(O_2\) \(\rightarrow\) \(Fe_2O_3\)
Unit Cumulative Exam
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Atomic Alchemy • Cumulative Assessment
Unit Exam: Molecular Shifters
Document ID: EXAM-1.00
Points: 50 Total
3 Particulate Rearrangements (10 Points)
Draw particle representations to contrast physical changes and chemical changes. Draw exactly 4 molecules of water (\(H_2O\)) in each box.
PHYSICAL: LIQUID WATER TURNS TO STEAM
CHEMICAL: WATER SPLITS INTO \(H_2\) AND \(O_2\)
4 Thermodynamics Synthesis (10 Points)
Review the chemical equation of propane combustion: \([ C_3H_8 + 5 O_2 \rightarrow 3 CO_2 + 4 H_2O + \text{Heat} ]\)
A. Is this reaction endothermic or exothermic? Explain how you know from the equation.
B. Contrast the total bond strength of products compared to the reactants.
Unit Cumulative Exam
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Heat Hunters Teacher Guide Atomic Alchemy • Unit 4
Heat Hunters Teacher Guide
TEACHER COMPANION
Pacing: 60 Minutes
Focus: Heating Curves & Exam
Subject: High School Chem
Lesson Objectives
Identify the values of \(\Delta H\) on potential energy diagrams to determine endothermic or exothermic reactions.Map states of matter and phase transition plateaus directly onto standard heating curves.Evaluate student mastery of Unit 1-4 objectives with the provided summative unit exam.
Master Answer Keys
Worksheet Solutions
Part 1 (Diagram): Reactants = 50 kJ; Products = 100 kJ; \(\Delta H\) = +50 kJ; Process = Endothermic .
Part 2 (Curve): A = Solid; B = Melting; C = Liquid; D = Boiling; E = Gas.
Part 2 (D vs B): Vaporizing requires breaking all intermolecular forces, which demands more heat than melting.
Unit Exam Master Key
Part 1 Multiple Choice:
Q1 = C (Water vapor condensing)
Q2 = B (Equal to reactants sum)
Q3 = A (Added energy breaks IMFs)
Part 2 Balancing:
\(\mathbf{4} Fe + \mathbf{3} O_2 \rightarrow \mathbf{2} Fe_2O_3\)
Part 3 & 4 Exam Grading Guidance
Part 3 (Liquid water to steam drawings): Solid/liquid drawing has clusters at beaker base. Steam drawing has individual water molecules spaced widely filling the top area.Part 3 (Water splits to H2/O2 chemical): Requires drawing separated individual atoms rearranging to form diatomic pairs of \(H_2\) (\(\circ\text{-}\circ\)) and \(O_2\) (\(\bullet\text{-}\bullet\)) rather than intact \(H_2O\) shapes.Part 4 (Propane combustion): Exothermic . Heat is on the product side (released). Products have lower potential energy (tighter bonds) compared to reactants.
Unit 4: Heat Hunters
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