Unit 3: Motion of Atoms and Molecules
Summative Performance Assessment
Subject: Honors Chemistry Study
Grade Level: 10/11
Unit: 3
Standards and Elements to be Assessed:
SC6: Students will understand the effects of motion and molecules in chemical and
physical processes
a. Compare and contrast atomic/molecular motion in solids, liquids, gases, and
plasmas.
b. Collect data and calculate the amount of heat given off or taken in by
chemical or physical processes.
c. Analyze flow of energy during change of state.
d. Gas Laws
Description of the Task:
Senator Ben Johnson from Wyoming is considering the introduction of a law which will
ban the sale and use of sparklers. Last summer, at a Fourth of July party his grandson, Miller,
received second and third degree burns on his hands, face, and feet from sparklers at the party.
His aide has contacted your company to gather evidence about the hazards of sparklers. Your
company has not only decided to produce a paper on the number of injuries due to fireworks and
sparklers but also has decided to have quality control run a variety of experiments on sparklers.
Your lab has been given the task of determining the amount of heat released per mole from the
combustion of magnesium: one component in sparklers.
Steps for completing the task:
Part 1: Background
Investigate sparkler composition, including the function of magnesium in sparklers. Investigate
the number of accidents due to fireworks, especially sparklers. Write a balanced, chemical
equation for the combustion of magnesium, including physical states. Predict whether the
reaction will be endothermic or exothermic and explain your choice.
Because the combustion of magnesium releases energy in the form of light energy, it is too
difficult to determine the heat of combustion for magnesium directly, using a calorimeter. It will
be necessary to use Hess’s Law.
Part 2: Lab Preparations
Your quality control team must design a series of different experiments that will be used to
determine the combustion of magnesium. The experiments will use a calorimeter to determine
the ΔH for each reaction. The team will then combine the equations for each experiment and, by
using Hess’s Law of Summation, determine the standard of heat of combustion of magnesium.
Complete the following prelab questions:
1. Calculate the volume of oxygen gas, at STP, that would be required to completely burn
0.12g of Magnesium.
2. Calculate the molar volume of oxygen gas (L/mol) under standard conditions (25oC and 1
atm).
Part 3: Designing the experiments
NOTE: Include safety precautions for each procedure.
Three reactions are listed below which could be used to find the combustion of magnesium using
Hess’s Law of Summation:
Reaction 1: The formation of liquid water from its elements.
Identify the type of reaction.
Using the table in your book, write a balanced equation for the formation of one mole of
liquid water from its elements. Include the energy term for the standard heat of
formation.
Reaction 2: Solid magnesium oxide reacts with aqueous hydrochloric acid
Identify the type of reaction.
Write a balanced equation for this reaction, including physical states.
Using a foam cup calorimeter, design an experiment and write a procedure to determine
the heat of Reaction 2. Identify the system and the surroundings. Include the steps and
calculations needed to find ΔH for the reaction. To conserve materials, you will be given
100mL of acid and 1.0 grams of magnesium oxide for the experiment.
Reaction 3: Magnesium metal is added to aqueous hydrochloric acid
Identify the type of reaction.
Write a balanced equation for this reaction and include the physical states. Using a foam
cup calorimeter, design an experiment and write a procedure to determine the heat of
Reaction 3. Identify the system and surroundings. Include the steps and calculations
needed to find the ΔH for the reaction. To conserve materials, you will be given 100 mL
of acid and 0.5 grams of magnesium.
**Submit your plan to your supervisor for permission to perform the experiments**
Part 4: Conduct the experiments
Your group will be given two days in which to complete your approved experiments. You will
need to create a data table for each reaction in which to record all observations and data collected
during the experiment.
Part 5: Post-lab questions
1. Your team has determined the heat of combustion for magnesium as it burns. However,
you are still concerned about the safety of a hot sparkler immediately after it goes out. If
a sparkler burns at 2200oC and leaves a residue of 0.18 g of magnesium oxide, how much
energy is released by the magnesium oxide as it cools to room temperature (25oC)?
(specific heat of magnesium oxide=0.822J/goC) According to your answer, is it safe to
touch a sparkler immediately after the flame goes out? Explain.
2. Considering the kinetic theory, describe the change in particle motion and potential
energy for Reaction 1 (the formation for liquid water from oxygen gas and hydrogen
gas). Comment on the formation of chemical bonds and the change in state of matter.
Specific Grading Criteria Checklist:
The student will:
___Research the number of accidents due to sparklers and their composition (1-2 pages)
___Include a works cited section (2-4 reliable sources--NO Wikipedia or general encyclopedia)
___Write a balanced equation for the combustion of magnesium
___Predict whether the combustion of magnesium will be endothermic or exothermic
___Complete prelab questions
___Experimental plans approved by teacher
___Perform each experiment as a group
___Abide by established laboratory safety rules
___Write a balanced equation for the formation of liquid water from its elements, including ΔH.
___Devise a lab procedure to find ΔH for the reaction of magnesium oxide and hydrochloric
acid.
___Write the balanced equation for the reaction between magnesium oxide and hydrochloric
acid.
___Devise a lab procedure to find ΔH for the single replacement reaction of magnesium and
hydrochloric acid
___Write the balanced equation for the reaction between magnesium and hydrochloric acid
___Use Hess’s Law to calculate the heat of combustion for magnesium. Show work for
combining reactions and all calculations.
___Calculate percent error (look up the accepted value for ΔHof for magnesium oxide and
compare) and report sources/reasons for error.
___Propose improvements to experimental procedure to reduce the percent error.
___Complete postlab questions.
___Collaboratively write a lab report that presents results from experiments.
___Use significant figures for all measured values.
___All measured values recorded in a data table.
___Data tables initialed by teacher, DAILY.
___Honor code statement in the header of the report.
___Each person must write a conclusion in their own words. This summary is your individual
work.
Combustion of Magnesium Lab Rubric
Lab Preparation (5pts)
_____ Prepared to work (has all required materials including lab book and procedures)
_____Obtains teacher signature for approval of procedures
_____Records data in lab notebook
Lab Safety and Cleanup (10pts)
_____Finishes lab in time allotted and remains on task
_____Obtains clean-up initials
_____Abides by safety rules and regulations during lab
Background Research (20pts)
_____Lab report typed (calculations/formulas may be NEATLY hand-written)
_____Background includes all portions (research of composition of sparklers, fireworks
accidents, endo/exo prediction, balanced equation for combustion of magnesium, and
prelab questions-show work)
_____Works Cited page
Procedures (10pts)
_____Step by step procedures for Rxn 2 (logical and easy to follow)
_____Step by step procedures for Rxn 3 (logical and easy to follow)
Balanced Equations and Type of Reaction (10pts)
_____Balanced equation and heat for Rxn 1
_____Balanced equations for Rxn 2
_____Balanced equation for Rxn 3
Data Tables (15pts)
_____Data table for Rxn 2 (includes all appropriate values and teacher initials)
_____Data table for Rxn 3 (includes all appropriate values and teacher initials)
Calculations (15pts)
_____Calculations for ΔH for Rxn 2
_____Calculations for ΔH for Rxn 3
_____Calculations for Hess’s Law
Post-lab questions (5pts)
_____Complete post lab questions (show work)
Summary (10pts)
_____Each individual writes their own summary (states the chemical concepts in the lab and
how the lab demonstrated that chemical concept)
_____Report percent error and identify sources of error and possible modifications
Total Points Earned____________