Research Question:
How does the mass of baking soda (1g, 2g, 3g, 4g, 5g) affect the temperature change (±1°c), using a thermometer, in the endothermic reaction of the citric acid solution (10 ml) after 90sec?
Background information
“When energy is taken in from the surroundings, it’s called an endothermic reactions”(BBC). Endothermic reactions take in heats from its surrounding to create bonds. Endothermic reactions are commonly found when using fridges and trying to heal sport injuries using an ice pack or cold pack. The ice packs endothermic reaction happens slowly and will need the ice pack to lay in the freezer over night, where as a cold pack will just need a snap to activate the endothermic reaction and can be left out anywhere. Cold packs get cold by random motion. A cold pack contains a solid compound and water; often the solid compound is ammonium nitrate (NH4NO3). In a cold pack ammonium nitrate (NH4NO3) and water (H2O) are separated by a barer but once the cold pack get activated by that snap the barer is broken and the two compounds reacts to one another creating an endothermic reaction. Endothermic reactions take in heat when the ammonium nitrate and water reacts to each other, the forces gets weakened and separates interactions making both particles slow down cooling down the mixture. After a cold pack is used it cannot be reused because the solid dissolves into the water and cannot be precipitated back to its original forms. This relationship between cold packs and our experiment is to see how an endothermic reaction can happen instantly or after a long period of time using different materials.
Independent Variables Dependent Variables
Mass of baking soda
(1g, 2g, 3g, 4g, 5g) Temperature change (Endothermic)
Measured in °C
Uncertainty: ±1°c
Control Variables
Name of Variable
Why do we need to keep this the same? How will I ensure it will stay the same? What tools & procedures are needed?
Temperature of room
The temperature of the room can affect the results in a negative way because we are doing an endothermic reaction experiment. If the temperature is to warm during one of the trials the temperature could stay the same to what we started with. Depending on the experiment heat can be considered catalyst. A few minutes before the experiment starts I will keep the room temperature as 23°C and keep the air-conditioning on through out the experiment.
Materials used
Materials used needs to be the same for the results to be fair I will need to have the same boiler tube not bigger and not smaller. If I were to use a beaker instead of a boiler tube it wouldn’t over flow and the substances would stay in the beaker instead of bubbling up as much as it should. I will make sure to have the same items by double checking the signs and names of the materials and when cleaning the supplies making sure to have an eye on my materials so I don’t get someone else’s.
Amount of citric acid used
For all our trials we will use 10ml of citric acid if we were to use a larger amount during one trial that trial would either become colder than expected or could cause implications that we did not account for. To insure that we have the same amount of citric acid I will pour the citric acid into a 10ml test tube before transferring it into a boiler tube.
Time
Time can have a huge impacted on the experiment because to short of time could give us the exact same temperature as we had at the beginning of the trial and to long of time could cause the mixture to heat up to room temperature. To make sure that we have the right amount of time I decided to have the timer at 1 minute and 30 seconds because 30 seconds is too short to see an accurate result and 2 minutes is too long and can cause the mixture to heat up or become the same temperature as the beginning of the experiment.
Concentration of citric acid
If we had different concentrations of the citric acid we could either get a bigger reaction or the mixture could have cooled down even more than expected. If we were to have the concentration of citric acid my independent variable should have been concentration of citric acid instead of mass of sodium bicarbonate. To ensure we have the same amount of concentration of citric acid in one container I will have enough citric acid to last for the entire experiment because its in one container the concentration of citric acid cannot change unless I accidentally pour water or more undiluted citric acid within it. The concentration we will be using for the experiment will be 0.2M only.
Cleaning the materials thoroughly
I will need to cleanse my materials out thoroughly because the school does not have enough materials to do the experiments in 15 separate boiler tubes or 15 measuring boats for all the students. If we do not clean the materials out properly for each trial the citric acid could become diluted or we will have extra sodium bicarbonate that could impact our results. To make sure we do not dilute the mixture I will pour the already activated trial into the waste bowl that’s accessible to everyone and then rinse out the boiler tube with a water and with a dry paper towel I will slowly push it into the boiler tube and clean out any excess water.
Hypothesis
I predict that by increasing the amount of sodium bicarbonate (1g, 2g, 3g, 4g, 5g) the temperature change will decrease as a result of it being an endothermic reaction. I believe this is true because of the sodium bicarbonate and the citric acid that’s mixed with water “reacts to form of sodium citrate (Na3C6H5O7), water, and carbon dioxide”(TeachEngineering).
C6H8O7 + 3NaHCO3 → Na3C6H5O7 + 3H2O 3CO2
Citric acid Sodium bicarbonate Sodium citrate Water Carbon dioxide
If we were to have pure citric acid and sodium bicarbonate the endothermic reaction would have taken a longer time for those to compounds to become a solid or reach a negative temperature but since we are using a diluted citric acid with water the process of dissolving and freezing will occur significantly faster. Most endothermic reactions will contain toxic chemicals in our experiment the most toxic is citric acid. Once the citric acid reacts to the baking soda the two starts to take in heat and slowly start to decrease in temperature there should be a fizzing on top to show that there is a chemical reaction-taking place.
Material Lab set up
Material Name Uncertainty Quantity/ volume
Boiler tube (22 ml) 3x
Thermometer ±1°c 1
Timer (90 sec) ±1 second 1
Electronic Balance Scale ± 0.4g 1
Citric Acid 150ml
Baking soda (Sodium Bicarbonate) 45g
Plastic measuring boats ±0.5 g 2
Spatula 1
Pipette 1
Test tube (10 ml) ±0.2 ml 1
Test tube rack
Method & safety
Cleapss / safety
Substance Hazard Emergency actions Additional Comments
Diluted Citric Acid (0.2 M) Low Hazard → If citric acid gets in your eye run you eye under a running faucet if still reddened or hurts consult a doctor.
→ Citric acid can cause irritation to the skin if allergic or gets into an open wound.
→ Citric acid can be found in different fruits such as lemons, limes, and oranges.
→ lemons contains the most citric acid in them with up to 0.25M
Sodium bicarbonate Low Hazard → Not harmful on skin or digested unless a harmful acid is involved.
→ If you get baking soda/sodium bicarbonate in the eye, gently run your eye under tap water if it gets worse see a doctor. → Sodium bicarbonate is often used in food items or products e.g. Baking goods (Chocolate chip cookies), sodas (Coca cola), or food colouring.
Colour code
Red – Safety
Blue – Independent variables
Orange – Dependent variable
Green – Control variable
Black – Detailed steps
Method
1. I turned on the air conditioning on and set it to 23°C and will not turn the AC off.
2. I put on my safety equipment (lab coat & goggles).
3. Make sure the room temperature is 20°c though out the experiment.
4. I collected all my materials and plug my electronic scale.
5. I grabbed the boiler tubes and placed them into a test tube rack.
6. I added 10ml of citric acid in the 10ml test tube and then poured it into the first boiler tube. (To this for the rest of the boiler tubes and make sure its 0.2M)
7. I placed the thermometer into the boiler tube and let it sit for 15 second.
8. I checked the temperature of the citric acid and recorded it into my book.
9. Leave the thermometer in the citric acid through out the experiment.
10. I put the measuring boat on the scale and reset the scale to make sure the scale said 0g so while I pour the sodium bicarbonate into the measuring boat on the scale will not give me a higher weight then what I need.
11. On the hollow part of the measuring boat I will slowly add 1g of baking soda into the measuring boat with the spatula.
12. With the measuring boat that contains 1g I slowly walk back to my working space to be ready to pour the sodium bicarbonate into the citric acid mixture.
13. I pre-sat the time to 1minute and 30seconds.
14. Once I had 1 gram of baking soda I slowly added the baking soda into the citric acid and started the timer.
15. Let the mixture sit without touching it and allow the time to run out.
16. Once the timer had run out I checked the temperature with the thermometer that had sat there through out the experiment.
17. I recorded my results in my book next to the previous results (The citric acid without any extra mixtures in it).
18. After recording my results I calculated the temperature change.
19. With the other 2 boiler tubes I did step 6 to 17 over for my independent variable.
20. I cleaned my materials for my next trials.
21. I re did steps 5 to 19 for all my other independent variable (1g, 2g, 3g, 4g, and 5g)
Raw Data
Title: The temperature before and after/ temperature change between the two degrees
T/C= temperature change
Temperature and temperature change
Trial 1 Trial 2 Trial 3
T/C Before After Change Before After Change Before After Change
1g 21° 18° -3° 21° 19° -2° 21° 18° -3°
2g 21° 18° -3° 22° 19° -2° 22° 19° -2°
3g 21° 19° -2° 22° 19° -2° 21° 18.5° -2.5°
4g 21° 19° -2° 21° 18.5° -2.5° 21° 18° -3°
5g 21° 19° -2° 21° 18° -3° 22° 19° -2°
Qualitative data
For each trial after pouring in the sodium bicarbonate into the citric acid mixture there was a quick reaction causing the mixture to fizz up and overflow, approximately 0.5 seconds right after we poured the sodium into the citric acid. Shown in the image on the left was the reaction and when it overflowed and on the image on the right shows after the bubbles faded and left a citric sodium mix that was grainy. From the experiment I could see that the sodium bicarbonate did not dissolve fully. The reaction of the experiment causing the bubbling brings the sodium bicarbonate powder up with the citric acid that had already reacted to about half of the sodium bicarbonate and the bubble that overflowed the boiler tube popped leaving the sodium bicarbonate and citric acid into a grainy mixture.
Final Process data table
Title: The average temperature change for the
increase in sodium bicarbonate. Data processing
Mass of sodium bicarbonate Average Temperature change Data processing is finding the average from the trials you have done. To get the averages you add all the first samples together so in this case the temperature change in 1g and then divide it by 3 because we only did 3 trials for each.
1g=-3-2-3=-8/3=-2.67 (rounded to the nearest 100ths)
Our average for 1g would be ≈-2.67
1g -2.67
2g -2.33
3g -2.17
4g -2.5
5g -2.33
Percentage error
Scale : 0.4/g x 100
1 g: 1/-2.67 x100
MB 0.5/gx100
Tt: 0.2/10 x100
Sw 1/90 x 100
Standard deviation
Graph
Conclusion
Evaluation
Work sited:
Background information:
BBC. "Exothermic and Endothermic Reactions – AQA." BBC, © 2018 BBC, www.bbc.com/bitesize/guides/z2b2k2p/revision/1. Accessed 27 Nov. 2018.
"The Chemistry of Cold Packs." youtube.com, uploaded by John Pollard, Ted-Ed, 11 Sept. 2014, ed.ted.com/lessons/how-do-cold-packs-get-cold-so-fast-john-pollard. Accessed 27 Nov. 2018.
Hypothesis:
CREAM GK-12 Program, et al. "Reaction Exposed: The Big Chill!" Techengineering.org, Engineering University Of Colorado Boulder, 26 Aug. 2018, www.teachengineering.org/activities/view/wsu_big_chill_activity1. Accessed 27 Nov. 2018.
Fourier Education. "Endothermic Reactions Citric Acide and Baking Soda." Issuu.com, Issuu Inc, 19 May 2016, issuu.com/einsteinworld/docs/endothermic_reactions_-_citric_acid.
Helmenstine, Anna Marie, PH.D. "Create an Endothermic Reaction." Thoughtco, Dotdash, 28 Sept. 2017, www.thoughtco.com/create-a-safe-endothermic-chemical-reaction-602207. Accessed 27 Nov. 2018.
QuestaCon. "Fizzy Sherbert." Questacon.edu.au, © Commonwealth of Australia 2018, www.questacon.edu.au/outreach/programs/science-circus/activities/fizzy-sherbet. Accessed 27 Nov. 2018.
Cleapss:
Cleapss. "Citric, Oxalic & Tartaric Acids." Cleapss.org.uk, ©CLEAPSS 2018, science.cleapss.org.uk/Resource/SSS025-Citric-oxalic-and-tartaric-acids.pdf. Accessed 26 Nov. 2018.
CLEAPSS. "Sodium and Calcium Carbonates." Cleapss.org.uk, ©CLEAPSS 2018, science.cleapss.org.uk/Resource/SSS033-Sodium-and-calcium-carbonates.pdf. Accessed 26 Nov. 2018.