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

2. The reaction of solid sodium hydroxide and dilute hydrochloric acid:

NaOH(s) + H+(aq) + Cl-(aq) Na+(aq) + Cl-(aq) + H2O(l) + heat

3. The reaction of sodium hydroxide solution with dilute hydrochloric acid:

Na+(aq) + OH-(aq) + H+(aq) + Cl-(aq) Na+(aq) + Cl-(aq) + H2O(l) + heat

Objective: To measure and compare the amounts of heat involved in three separate but related reactions to provide experimental verification of Hess’s Law.

Materials: Thermometer

Styrofoam cup

Solid NaOH

0.50M NaOH(aq)

0.25 M HCl(aq)

0.50 M HCl(aq)

Reaction One: The Dissolving of Solid Sodium Hydroxide in Water

  • Put 200 mL of distilled water into the styrofoam cup. Measure and record the temperature.
  • Record the mass of approximately 2.00g solid sodium hydroxide. Transfer it into the water in the styrofoam cup. DO NOT TOUCH THE SOLID SODIUM HYDROXIDE WITH YOUR HANDS. Stir gently with the thermometer until the solid is completely dissolved and record the highest temperature reached.
  • Discard the solution in the disposal beaker on the front bench and rinse the cup thoroughly with tap water.

Reaction Two: The Reaction of Solid Sodium Hydroxide with Hydrochloric Acid Solution

  • Put 200 mL of .25m HCl into the styrofoam cup. Measure and record the temperature.
  • Record the mass of approximately 2.00g solid sodium hydroxide. Transfer it into the .25M hcl in the styrofoam cup. Stir gently with the thermometer until the solid is completely dissolved and record the highest temperature reached.
  • Discard the solution in the disposal beaker on the front bench and rinse the cup thoroughly with tap water.

Reaction Three: The Reaction of Sodium Hydroxide Solution with Hydrochloric Acid Solution

  • Accurately measure 100 mL of 0.50 M HCl into the styrofoam cup and 100 mL of 0.50 M NaOH into a 250 mL beaker. Record the temperatures and volumes of each solution.
  • Add the NaOH solution to the HCl solution in the cup. Stir the mixture with the thermometer and record the highest temperature reached.
  • Discard the solution down the sink, and rinse both containers well.

Calculations: From your data, calculate the following for each part of the experiment:

  • The temperature change of the liquid (Δt).
  • The heat absorbed by the solution (Q = mcΔt: assuming that the specific heat capacity of the solution is approximately equal to that of water and that the density of the solutions are equal to that of pure water).
  • The number of moles of sodium hydroxide present.

Write a report highlighting these three questions :

1.  Add the ionic equations given for part one and part three. Compare the result with the ionic equation for part two.

2.  Compare the sum of the heats of reaction for parts one and three with that obtained for part two. In light of your answer to question #2, explain your results here.

3.  Discuss Hess's Law in terms of the Law of Conservation of Energy and in terms of the three parts of this experiment.

Data entry tables for calculation

1.NaOH(s) NaOH(aq)

Mass of NaoH taken(g) / Initial temp of water / Final temp of solution / ΔT / ΔH for reaction A

2.NaOH(s)+HCl(aq) NaCl(aq)+ H2O(l)

Mass of NaOH(g) / Initial temp of HCl / Final temp of solution / ΔT / ΔH for reaction B

3.NaOH(aq)+HCl(aq) NaCl(aq)+ H2O(l)

Initial Temp of Hcl / Final temp of solution / ΔT sol / ΔH for reaction C

Calculate ΔH for all three reactions and prove Hess’s law

Part B : Application of rates of reaction and factors affecting rates of reactions

Write a report on practical application of day to day life featuring effect of temperature, catalysts, concentration on rates of reactions. Explain how your application makes an impact on society and technology in the real world.

Or

Give a power point presentation on rates of reactions and factors affecting them illustrating practical examples. Explain how your examples make an impact on society and technology in the real world.

Here are just a few everyday demonstrations that temperature changes the rate of chemical reaction:

  • Cookies bake faster at higher temperatures.
  • Bread dough rises more quickly in a warm place than in a cool one.
  • Low body temperatures slow down metabolism. In fact, warm-blooded animals regulate body temperature so that their biochemical reactions run at the correct rate. (Homeostasis)
  • Growth of micro organisms stop at low temperature
  • Washing of clothes at optimum temperature

Increasing the concentration of reactants also changes reaction rate:

  • Two antacid tablets will neutralize a given amount of acid faster than one tablet will. Higher con
  • centrations of acid in rain erode marble faster than lower concentrations.


General instructions and precautions

  • Record your instructions once you complete experiment
  • Spillage of chemicals/reagents should be cleaned immediately and safely
  • Always maintain cleanliness at your work station
  • Wash and handle apparatus(glassware ) carefully
  • After finishing your experiment, turn off instrument used
  • Avoid wastage of water
  • Maintain good lab practice
  • In case of swallowing of a chemical, tell lab in charge immediately
  • Always wear proper PPE in lab
  • No eatables allowed in lab
  • No loose clothes or open hair in lab

Resources for Part A

  • http://www.instruction.greenriver.edu/kmarr/Chem%20161/Chem%20161%20Labs/Lab%209%20Hess's%20Law/Lab%209_Hess's%20Law_Vernier_Report%20Sheet_F2009.pdf
  • http://www.wiziq.com/tutorial/179525-Chemistry-Laboratory-Manual
  • For ELL students
  • http://www.youtube.com/watch?v=8yFjgAtB8yg

Resources for Part B

http://www.scienceclarified.com/everyday/Real-Life-Chemistry-Vol-1/Temperature-and-Heat-Real-life-applications.html

For ELL students http://www.youtube.com/watch?v=izqJkdj1d4U

http://www.slideshare.net/Emersius/rate-of-reactions

Discrepant event on rates of reaction

http://www.nipissingu.ca/education/geraldl/sciencegeneral/discrepant_events.htm

Assessment tools for Culminating Task

1.Peer evaluation: This evaluation will be done by students and every student will mention 3 names of students and will rate on these traits worth 5 points each. Top 3 students will get peer recognition award.

Name of student / Responsibility / organisation / Independent work / collabration / initiative

2.Rubric chart: for assessment by teacher

NOTE: Part A & B are both assessed for KICA, look under first column to see which part is assessed for each item.

Knowledge and Understanding / Level 1 (50-59%) / Level 2 (60-69%) / Level 3 (70-79%) / Level 4: (80-100%)
Part A: Knowledge of content of energy and rates of reaction
(e.g., facts, terminology,
definitions, numerical, lab work, etc.) / demonstrates
limited knowledge of
content / demonstrates some
knowledge of content / demonstrates considerable
knowledge of content / Demonstrates a high degree of knowledge of
of content
Part B: Can summarize topic and do research)
(e.g., concepts, ideas, theories, procedures,
processes etc.) / demonstrates
limited summary and research of the into the topic / demonstrates some summary and research of the into the topic / demonstrates considerable
summary and research of the into the topic / demonstrates
a high degree of summary and research of the into the topic
Inquiry / Level 1 (50-59%) / Level 2 (60-69%) / Level 3 (70-79%) / Level 4: (80-100%)
Part A: Use of initiating and planning skills and strategies
(e.g., formulating questions, identifying the problem, developing hypotheses,
scheduling, selecting
strategies and resources,
developing plans) / Completion of Hess’ Law experiment uses initiating
and planning
skills and
strategies
with limited
effectiveness / Completion of Hess’ Law experiment uses initiating
and planning
skills and
strategies
with some
effectiveness / Completion of Hess’ Law experiment uses initiating
and planning
skills and
strategies
with considerable
effectiveness / Completion of Hess’ Law experiment uses initiating
and planning
skills and
strategies
with a high degree of effectiveness
Part B: Use of critical/creative
thinking processes,
skills, and strategies
(e.g., analysing, interpreting,
problem solving, evaluating,
forming and researching) / Research into topic shows critical/creative thinking
processes, and connections to rates of reaction are made with limited effectiveness. / Research into topic shows critical/creative thinking
processes, and connections to rates of reaction are made with some
effectiveness. / Research into topic shows critical/creative thinking
processes, and connections to rates of reaction are made with considerable
effectiveness / Research into topic shows critical/creative thinking
processes, and connections to rates of reaction are made with a high degree of effectiveness.
Communication / Level 1 (50-59%) / Level 2 (60-69%) / Level 3 (70-79%) / Level 4: (80-100%)
Part A & Part B: Expression and
organization of ideas
and information
in oral, visual, and/or written forms ( clear expression, logical
organization in diagrams, models) / expresses and
organizes ideas
and information
with limited
effectiveness / expresses and
organizes ideas
and information
with some
effectiveness / expresses and
organizes ideas
and information
with considerable
effectiveness / expresses and
organizes ideas
and information
with a high degree of effectiveness
Part B: Communication to audience with the purpose of informing them oral, visual, or written forms. / Presentation of material in student’s choice of delivery method (report, presentation, etc.) was limited in clarity, logic & information to viewers. / Presentation of material in student’s choice of delivery method (report, presentation etc.) had some clarity, logic & information to viewers. / Presentation of material in student’s choice of delivery method (report, presentation etc.) had considerable clarity, logic & information to viewers. / Presentation of material in student’s choice of delivery method (report, presentation etc.) had a high degree of clarity, logic & information to viewers.
Part A & Part B: Use of conventions,
vocabulary, and
terminology of the
discipline in oral, visual,
and/or written forms
( e.g. Symbols, formula, scientific notation, chemical reactions etc.) / uses conventions,
vocabulary, and
terminology of the
discipline with
limited
effectiveness / uses conventions,
vocabulary, and
terminology of the
discipline with
some
effectiveness / uses conventions,
vocabulary, and
terminology of the
discipline with
considerable
effectiveness / uses conventions,
vocabulary, and
terminology of the
discipline with
a high degree of
effectiveness
Application / Level 1 (50-59%) / Level 2 (60-69%) / Level 3 (70-79%) / Level 4: (80-100%)
Part A: Application of
knowledge and skills
(e.g., concepts and processes,
safe use of equipment
and technology ,investigation
skills) in familiar contexts / Completion of Hess’ Law experiment shows that knowledge
and skills are applied in familiar contexts
with limited effectiveness. / Completion of Hess’ Law experiment shows that knowledge
and skills are applied in
familiar contexts
with some
effectiveness / Completion of Hess’ Law experiment shows that knowledge
and skills are applied in
familiar contexts
with considerable
effectiveness / Completion of Hess’ Law experiment shows that knowledge
and skills are applied in
familiar contexts
with a high degree of effectiveness
Part B: Transfer of knowledge
and skills (e.g., concepts and processes, safe use of
equipment and technology,
investigation skills) to
real life problems / Transfer knowledge and skills of chemical reactions to solve real-life problems with limited of effectiveness / Transfer knowledge and skills of chemical reactions to solve real-life problems with some of effectiveness / Transfer knowledge and skills of chemical reactions to solve real-life problems with considerable effectiveness / Transfer knowledge and skills of chemical reactions to solve real-life problems with a high degree of effectiveness
Part B: Made connections between science, technology,
society, and the
environment, and proposed of practical action to
deal with problems
relating to science,
technology, society,
and the environment. / Related to their research topic, student makes connections to technology and society with limited effectiveness / Related to their research topic, student makes connections to technology and society with some effectiveness / Related to their research topic, student makes connections to technology and society with considerable effectiveness / Related to their research topic, student makes connections to technology and society with a high degree of effectiveness

Resource for assessment tool

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