_CHEM_ Decarbonating Soda Water

Decarbonating Soda Water – Report

Decarbonating Soda Water

Aim: To investigate the amount of carbon dioxide lost when a carbonated beverage is degassed.

Hypothesis: The carbonated beverage will lose carbon dioxide upon the addition and mixture of salt. It will be impossible to degas the beverage completely.

Equipment: 1.5L soda water bottle (1 per group;

refrigerated; a lemon soda bottle of the same specified volume was used) [actual instructions recommended a 300ml soda water bottle]

4 L beaker Glass rod (for stirring; a teaspoon was

used instead) 50ml beaker (for carrying and

measuring the salt) [actual instructions specified 6g of salt. The

amount was scaled up with respect to the new volume of 1.5L. After adding, it was found that the beverage was still effervescing, hence the extra 20g of salt, totalling up to 50g)

50g of salt Electronic balance 4 500 ml beakers (for measuring the

weight of the lemon soda afterwards [some electronic balances are unable to measure objects greater than 4kg])

Procedure : 1) Prepare all required equipment: electronic balance; 50g of salt (contained in a 50ml beaker),

etc. 2) Weigh an unopened soda water bottle on an electronic balance. Record the weight. 3) Weigh a clean, dry 4L beaker. Record the weight. 4) Unscrew the lid of the soda water bottle and slowly pour all its contents into the beaker.

Once added, place the beaker on the electronic scale to measure and record the new weight.

5) Remove the beaker from the balance. Add the 50g of salt to the 4L slowly while mixing with the glass rod to assist degassing.

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6) After 10 minutes, weigh the beaker and its contents. Continue to stir for several minutes. Repeat the weighing after 30 minutes, but which time the soda water should have gone flat. Note: if unable to measure the beaker and the soda water, pour the contents of the 4L beaker into 4 separate 500ml beakers that have been pre-measured on the electronic balance. Upon pouring the flat soda water into the beaker, weigh all four beakers. From this, it is possible to calculate the new weight of the soda water upon being degassed.

7) Meanwhile, reweigh the dry soda water bottle and cap; make sure to keep the residual contents of the soda water bottle inside while weighing to lessen any possible error margins.

Safety Precautions : Risk Factor Hazard ControlLemon soda (moderately acidic)

Eye irritation on contact, mild skin irritation upon long exposure, mild irritation through respiratory tract.

If in the eyes, flush the point of contact with water; upon skin contact wipe the sample with a cloth or run under water; if soda water vapours an inhaled, take a few breaths in an area further away from the soda water to respire any remaining vapours.

Prevention: Handle the soda water carefully; wear safety glasses throughout the experiment; take basic lab safety precautions, i.e. handling glassware carefully, etc.

Shattered glass (if a test tube or beaker is broken)

Cuts and/or scratches. Run the cut under clean water to get rid of possible contaminants, sterilise the cut using antiseptics, and apply a bandage to the wound to prevent infection.

Prevention: Handle glassware equipment carefully to prevent further breakage; alert a supervising teacher instead of risking (further) injury; take basic safety precautions when handling glassware.

Results: Measuring the weight of the unopened soda water bottle and 50g of salt:Equipment of Materials Initial

Weight (grams)

Final Weight (grams) [upon emptying the bottle or upon the addition of salt to the soda water]

Unopened lemon soda bottle (i.e. with lid) 1614.1 47.650g of salt (upon putting it on the electronic scale, the beaker’s weight was re-zeroed, causing the beaker to have a displayed weight of zero, allowing for the accurate measurement of salt)

50 -- (all dissolved)

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Measuring and calculating the weight of the degassed or flat soda water containing 50g of salt: Equipment or Materials

Initial Weight (grams)

Final Weight (grams) [with the addition of soda water]

Weight of the soda water [initial weight – final weight] (ml)

4L beaker 1000 -- (the electronic balance at hand was unable to measure objects greater than 4kg in weight)

--

500ml beaker 187.8 680.1 492.3500ml beaker 215.5 716.7 501.2500ml beaker 229.0 699.5 470.5250ml beaker 123.9 241.8 + 3 (244.8) (Upon pouring,

approximately 3ml of soda water was spilt, hence the addition of 3ml of water)

120.9

Total amount of flat lemon soda water: 1584.9

Initial amount of lemon soda = 1614.1 – 47.6 = 1566.5g

Final amount of flat lemon soda without salt = 1584.9 – 50 =1539.9g

Change in mass after salting out the lemon soda (i.e. CO2 lost) = initial – final = 1566.5 – 1539.9 = 35.6g

Number of moles of CO2 lost (i.e. n of CO2) = m/MM = 35.6/44.01 = 0.8089070666 moles

Volume of evolved CO2 (at 25⁰C and 100kPa): n = V/Vm

0.8089070666 = V/24.79 V = 20.05280618L V = 20.05L (2 d.p.)

Discussion: Coinciding with the hypothesis, the carbonated beverage lost carbon dioxide upon the addition of salt. It was virtually impossible to degas the beverage completely considering school laboratory conditions, available time and resources. An outwardly considerable amount of CO2 was degassed from the lemon soda beverage; however, upon consulting the supervising teacher and other sources, the final result was not an overall outlier.

As aforementioned, it was impossible to degas the beverage completely with respect to the time and resources that were available, despite repeated additions of salt. This facet was of some issue half-way through the experiment: the initial amount of salt was 30g and, upon observing further effervescence, mixed in an extra 20g, making 50g in total. Subsequently, the final weights were measured and there were no further opportunities for degassing available due to time constraints. The initial 30g was derived from the base worksheet via ratio, i.e. from the equipment section: Actual instructions specified 6g of salt. The amount was scaled up with respect to the new volume of

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1.5L. After adding, it was found that the beverage was still effervescing, hence the extra 20g of salt, totalling up to 50g.

Reliability – The experiment had a low level of reliability as the experiment was only conducted once. Consequently, it would not necessarily represent how similar experiments proceed or have identical results regarding the degassing of carbon beverages.

However, when comparing the procured the results with those provided by the teacher, there was a slight increase in the reliability of the results given that they were similar. There were no other groups in the class that conducted the experiment due to class size and the limited amount of time and resources at hand.

The reliability of the experiment could be improved by repeating it a great number of times.

Validity – In the experiment, the variables were as follows: Independent variable: Salt added to the carbonated beverage. Dependent variable: Amount of CO2 released from carbonated beverage. Controlled variable: The atmospheric conditions (stable lab conditions), amount of

carbonated beverage being used, the exact amount of salt added to the beverage, the measuring instrument (same one used throughout).

The controlled variables were maintained throughout the experiment, but there was an issue relating to the number of assumptions made in preparing the planning the experiment. Theoretically, the experiment had a high level of validity if the following assumptions remained undisputed:

The glassware equipment was not contaminated. Contamination would possibly lead to skewed and invalid results, influencing the chemical constitution of the beverage and, thus, affecting the concluding result. Such might have been an issue as none of the beakers were cleaned before being used.

An inconsiderable amount of CO2 was lost before the initial weighing—if a significant amount was lost, the results gathered would be invalid. However, if the experiment is repeated in the future, the results would be accumulatively reliable, if not accurate or valid.

The amount of salted water lost was properly replaced. While this was unlikely, the concluding results were similar to those gathered by the supervising teacher.

There were no residual amounts of beverage in the bottle or the 4L which would, in turn, affect the results and the concluding calculations. This was an inevitable issue when pouring the beverage out of the bottle, and was exacerbated by the separate measurements of the salted beverage in different beakers.

Overall, it is discernible that the experiment has a medium level of validity as it only relied on a number of assumptions. Concurrently, it was the best that could be done with the limited amount of time and resources.

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The validity could be improved through various means such as: cleaning the glassware to prevent contamination; weighing the beverage’s initial weight quickly when poured into the beaker (or, more efficiently, the unopened bottle could be weighed and, after the events of the experiment, the empty bottle could be weighed to then find the initial beverage mass); conducting the experiment carefully to prevent any spills which would affect the validity; using a smaller sample size (which would alleviate the damage done to the experiment’s validity, but effect the reliability), or instead using an electronic scale capable of measuring over 4kg (thus improving validity without impeding reliability).

Accuracy – The overall accuracy could not be evaluated as data was unavailable regarding the standard amount of CO2 in a 1.5L bottle. Concurrently, comparing the results to external sources would have been inaccurate due to the lack of standardisation in beverage carbonation. Notably, the concluding results were similar to those of the supervising teacher’s. Nonetheless, information from a single source did not constitute the means for a grounded evaluation of the experiment’s accuracy. With regards to the measuring instruments utilised in the experiment, there was a medium level of accuracy:

Electronic scale: The scale was used to measure the weight of the beverage before and after salting. Its maximum weight was 4kg, the final weight measurements had to be taken through other means, i.e. pouring the contents of the 4L beaker into the other beakers. Since the scale gave digitally numerical readings on what was being weighed, it was accurate to 0.01 grams. As a digital scale, this meant that it was relatively accurate.

Ultimately, the accuracy of the results was mainly influenced by limitations in the experiment’s validity and the transgressions made during the experiment. The beakers used in the course of the experiment were without mention as none of them were used for actual measurements, etc.

To improve the accuracy of the results and observations: by repeating the experiment a number of times until the results become consistent; by using the same scale for future repetitions.

Conclusion : In degassing a carbonated beverage, the amount of carbon dioxide lost was investigates. The beverage lost carbon dioxide upon the addition and mixture of salt. It was impossible to degas the beverage completely.

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_CHEM_ Decarbonating Soda Water