Presentation notes Flashcards
1 - Title Slide
• Leave up during build up
1 - Title Slide
Leave up during build up
2 - Introduction
Congratulations on projects
Challenging time in pandemic
Difficult for teachers and students – lack of labs
Developed home experiment to tackle this (KS5 level)
3 - Literature review
Initial research into of home experiments in literature
Common aims • Reinforced and richer learning • Principles of handling chemicals • Practice of scientific method • More accessible lab equipment • Preserve learning objectives
Benefits over normal labs:
• Reduced screen-time in pandemic
• Lower hazard risks
• Similar grade distributions
Difficulties:
• No specialist equipment for advanced experiments
• Lack of lab authenticity
• Sometimes too time consuming with courses
4 - Experiment overview
Focus on KS5 level for my experiment:
• Rely on labs to reinforce concepts and often more complex practicals
• Evidence of importance of lab work in elementary chemistry
Focus on kinetics
• Enjoyed at school and uni
• Complex topic students struggle with
Primary objective was for students to determine EA for the neutralisation reaction of
acetic acid and calcium carbonate
Hope to be engaging by links to everyday life
• Representative of neutralisation between antacid and stomach acid to relieve heartburn + acid indigestion
• Tums used as calcium carbonate
• Vinegar (acetic acid) used as hydrochloric acid
• Evidence in literature that using real life hands on samples in home experiments better than virtual reality as alternatives to in person labs
5 – Experiment design
Most difficult part –> designing efficient & simple gas collection method
Had to be applicable to home use
Best solution –> blu tack bung attached to plastic straws as the gas tube
Explored options –> cling film seal pierced with straws + other plastics e.g. bin bags
Blu tack one was best:
• Fewer gas leakages
• Easier to apply and reapply between runs
To my knowledge, first home experiment to use this kind of novel technique
6 - Method (Video)
Best way to demonstrate apparatus and procedure –> video
Video made to explain procedure and items needed to students
Tried to engage all learner types –> pay attention to music cues (elaborate later)
PLAY VIDEO
7 - Supporting information
Video just seen made in conjunction with handout
Handout similar to uni lab handouts: • Context to experiment • Explain theory • Goes through procedure and analysis • Asked KS5 level questions
Creating video tried to consider learning methods:
• Auditory learners –> music cues in video
• Visual learners –> seeing steps in video
• Kinesthetic learners –> hands on element of the practical
• Reading learners –> handouts
8 – Safety considerations
Careful consideration to be applicable for at-home use
Only mild risks –> mild skin + eye irritation from vinegar
Mitigated by wearing plastic gloves and safety specs
9 - Results and Analysis
After procedure in the video, students asked to find the Ea from their data
Analysis involved practice of the Arrhenius equation in the context of an initial rates method
The analysis therefore covered the UK curriculum topics of:
• Activation energy
• Reaction rate dependence on temperature
• Rate equations
The first step –> take initial readings (first 20-30 secs) of volume of CO2 and plot against time for each temperature run
• Method was applicable –> vol of gas produced was directly proportional to time in testing (R2 = 0.99), so tangent from t=0s in usual initial rates method was reflective of a trendline fixed at origin on the volume time graph
Calculate the gradient of each run to find the rate constant at each temperature
Complete Arrhenius plot of 1/T vs natural log of initial rate constant
Find the gradient of this plot and final the activation energy from this value
In my testing representative value was around 29 ± 4 kJ mol-1
10 - Errors
Repeat experiment found EA = 32 ± 4 kJ mol-1
• Therefore good tolerance to error
Most representative lit. value = 17 ± 3 kJ mol-1
• Therefore value was relatively good accordance
Differences to lit. value examples:
• Lit. value accounted for dissolving of CO2 gas back into water to give carbonic acid
• Experiment not in lab, therefore difficult to temp of each run without hot plate
• Using this gas collection method initial values often have high uncertainty
Despite this, main aim not to get accurate value –> focus on practise of scientific method and analysis whilst having fun
11 - Cost
Typical cost for 1 student is around £19 at current costs
High dependence on what apparatus students have at home
• If carried out by school –> apparatus in video e.g. thermometers and measuring cylinders could be provided
In the video I created my own measuring cylinder using spice jar and paper Average KS5 class size = 11 • Rough cost per student in a class around £9 assuming school is relatively well equipped with 11 thermometers and measuring cylinders • Cost to whole class would be around £100
12 - Feedback
To gauge student response and experimental outcomes –> video uploaded to YouTube
• Students could discover it here or use it to aid assigned experiment
• Allowed students to comment any feedback
Experiment given to KS5 teachers across UK –> received feedback from 4 so far
Initial feedback –> encouragingly positive
• Easy to follow
• Engaging
• Link to everyday life
• Something practical in a time without labs
• Simple equipment to demonstrate tricky concepts
13 - Improvements
Despite overall objectives achieved –> always room for improvement –> teacher feedback included:
• Importance of IUPAC naming (ethanoic acid not acetic acid), suggested asking a question about this
• Include table of results seen in video in the handout
• Adding timestamps to the video description to link with handout procedure
• Using mol and standard units not mmol (mmol not standard KS5 units)
• Extra resource for making homemade measuring cylinder, types of glass needed (tall + thin + uniform)
• Extra resource about use of other carbonate tablets if Tums not available, adjusting amounts for different carbonate contents
I also considered improvements myself:
• Environmental impacts of plastic straws –> use PLA biodegradable straws
• Using electric hob to maintain temp during readings
14 - Variations and Adaptations
Despite focus on KS5 age group –> developed a cut down experiment for KS3-4 ages
• Key objective to observe rate of reaction dependence on temperature
• Alternative handout was made so anyone could repeat it
• Not sent out for feedback due to time constraints
• Level of detail about why rate increases with temp can be controlled by teachers in post analysis questions
If performed in schools, may be better/alternative to use high precision mass balances and measure mass lost over time
• Less time consuming
• Better reliability
Future work could be to adapt the experiment to different acid types e.g. citric acid from lemons
• Different acids used in place of vinegar and activation energies calculated and results drawn
