Project 2 Final Lab Report PDF

Preview

Summary

Project 2: Quality Control, Analysis of Everyday Products...

Description

Victoria Telhada CHEM 2045L.019 April 4, 2017

Project 2: Quality Control, Analysis of Everyday Products Lab Report I.

INTRODUCTION: Background- In today’s world, every product, from food to cleaning products, has some type of label that displays the ingredients, supplement facts, etc. However, most of the time the labels lack accuracy. So to prevent unsatisfactory products from hitting the market, scientists can do a quality check to determine if the labels comprise of accurate facts. An example of this would be a scientist checking the sugar levels in a sugar free cookie to check if the cookie is actually sugar-free. By doing this, the scientist is ensuring the accurate ingredients in the product before its shipped to different stores.

Scientific Concepts- There were a few key scientific concepts that would be helpful to know before performing the experiment. The first concept would be an acid -base titration, this is usually used to find the amount of a known acidic or basic substance through acid base reactions. The analyte is the solution with an unknown molarity. The reagent (titrant) is the solution with a known molarity that will react with the analyte (2). The second concept would be solubility, this is when an ionic compound dissolves in water, the solution contains its component ions. However not all ionic compounds dissolve in water. Those compounds that dissolve in water are soluble and those that don’t are insoluble (11). The next concept is standardization, which is the the process of determining the exact concentration (molarity) of a solution. This can be achieved by doing procedures, such as a titration (7). The last and most important concept for this experiment is solution stoichiometry, this deals with quantities in chemical reactions taking place in solutions. When using this, concentration, volume, etc. can be calculated (13).

Hypothesis- The overall outcome of this experiment is to be able to conduct quality control on commercial products by doing quantitative tests to determine the accuracy of its concentrations.

Objectives- The week 1 objective is to standardize an NaOH, HCL, and KHP solution using acid-base titrations. The week 2 objective is to quantify the active ingredient in either vitamin C tablets or baking soda and another household product with an acid-base titration. II.

METHODS: A. Week 1 Methods Materials- 8.3 mL of NaOH, 8.3 mL of HCL, 8.3 mL of KHP, burette, burette stand, Bromothymol Blue Indicator, Bromocresol Purple Indicator, 3x 250 mL Erlenmeyer flask, 2x 300 mL Erlenmeyer flask

Procedure- The first step is to obtain all the materials listed. We began by preparing the solutions for NaOH, HCL and KHP. To prepare the NaOH Solution, 8.3 mL of NaOH was mixed with 250 mL of distilled water in a 300 mL Erlenmeyer flask. To prepare the HCL Solution, 8.3 mL of HCL was mixed with 250 mL of distilled water in a 300 mL Erlenmeyer flask. Lastly, to prepare the KHP Solution, 1g of KHP was mixed with 100 mL of distilled water in a 250 mL Erlenmeyer flask. To standardize the NaOH solution, an acid-base titration was performed with NaOH and KHP. For trial 1, we started with 50 mL of the KHP solution mixed with 6 drops of the Bromothymol Blue indicator in a 250 mL Erlenmeyer flask, to be titrated. In the burette, we started off with 25 mL of NaOH solution. For trial 2, we started with 20 mL of the KHP solution mixed with 3 drops of the Bromothymol Blue indicator in a 250 mL Erlenmeyer flask, to be titrated. In the burette, we started off with 10 mL of NaOH solution. For trial 3, we started with 20 mL of the KHP solution mixed with 6 drops of the Bromothymol Blue indicator in a 250 mL Erlenmeyer flask, to be titrated. In the burette, we started off with 10 mL of NaOH solution. Next, we calculated the NaOH concentration for each trial, using the equation 𝑀1 𝑉1 =𝑀2 𝑉2 , then calculated the average concentration from all three trials. After completing the titration, we stored the

standardized NaOH solution in a plastic bottle. To standardize the HCL solution, the same acid-base titration steps as above were performed but with NaOH. For all three trials, we started with 20 mL of the HCL solution mixed with 6 drops of the Bromocresol Purple indicator in a 250 mL Erlenmeyer flask, to be titrated. In the burette, we started off with 20 mL of NaOH solution. Again, after completing the titration we stored the standardized HCL solution in a plastic bottle. B. Week 2 Methods Materials- 2x 250 ml Beaker, 3x 250 Erlenmeyer Flask, 3x 50 mL Beaker, .42g baking soda, burette, burette stand, hot plate, NaOH standardized solution, HCL standardized solution, and .38g (or 1 pill) of aspirin.

Procedure-The first step is to obtain the materials and bring in a household product. We began by making a baking soda solution, which comprised of .42g of baking soda with 50 mL of water in a 250 mL beaker. Next, we performed an acid-base titration with the baking soda solution and the HCL standardized solution. For trial 1, we started with 10 mL of the baking soda solution mixed with 6 drops of the Bromothymol Blue indicator in a 50 mL beaker, to be titrated. In the burette, we started off with 20 mL of HCL solution. For trial 2 and 3,we started with 10 mL of the Baking Soda solution mixed with 6 drops of the Methyl Orange indicator in a 50 mL beaker, to be titrated In the burette, we started off with 15 mL of HCL solution. We calculated the concentration for each trial, using the equation 𝑀1 𝑉1 =𝑀2 𝑉2 , then calculated the average concentration from all three trials. Next, we used aspirin as our house hold product and made a solution with .38g of aspirin (approx. 1 pill) and 18 mL of distilled water. We then performed another acidbase titration with the aspirin solution and NaOH standardized solution. For trial 1 and 2, we started with 5 mL of the aspirin solution mixed with 6 drops of Bromothymol Blue indicator in a 50 mL beaker, to be titrated. In the burette, we started off with 15 mL of NaOH solution. For trial 3, we started with 2.5 mL of the aspirin solution mixed with 6 drops of Bromothymol Blue indicator in a 50 mL beaker, to be titrated. In the burette, we started off with 30 mL of NaOH solution. We calculated the concentration for each trial, using the equation 𝑀1 𝑉1 =𝑀2 𝑉2 , then calculated the average concentration from all three trials.

C. Safety1. Hydrochloric Acid: •

Very hazardous in case of skin contact (corrosive, irritant, permeator), of eye contact (irritant, corrosive), of ingestion, . Slightly hazardous in case of inhalation (lung sensitizer). Non-corrosive for lungs. Liquid or spray mist may produce tissue damage particularly on mucous membranes of eyes, mouth and respiratory tract. Skin contact may produce burns. Inhalation of the spray mist may produce severe irritation of respiratory tract, characterized by coughing, choking, or shortness of breath. Severe over-exposure can result in death. Inflammation of the eye is characterized by redness, watering, and itching. Skin inflammation is characterized by itching, scaling, reddening, or, occasionally, blistering (8).

2. Sodium Hydroxide: •

Very hazardous in case of skin contact (corrosive, irritant, permeator), of eye contact (irritant, corrosive), of ingestion, of inhalation. The amount of tissue damage depends on length of contact. Eye contact can result in corneal damage or blindness. Skin contact can produce inflammation and blistering. Inhalation of dust will produce irritation to gastro-intestinal or respiratory tract, characterized by burning, sneezing and coughing. Severe over-exposure can produce lung damage, choking, unconsciousness or death. Inflammation of the eye is characterized by redness, watering, and itching. Skin inflammation is characterized by itching, scaling, reddening, or, occasionally, blistering (12).

3. Potassium Hydrogen Phthalate: •

Slightly hazardous in case of skin contact (irritant), of eye contact (irritant), of ingestion, of inhalation (10).

4. Baking Soda: •

Slightly hazardous in case of skin contact (irritant), of eye contact (irritant), of ingestion, of inhalation (4).

5. Bromothymol Blue: •

Very hazardous in case of ingestion. Hazardous in case of skin contact (irritant), of eye contact (irritant), of inhalation. Slightly hazardous in case of skin contact (permeator) (5).

6. Bromocresol Purple: •

Slightly hazardous in case of skin contact (irritant), of eye contact (irritant), of ingestion, of inhalation (6).

7. Distilled Water •

Non-corrosive for skin. Non-irritant for skin. Non-sensitizer for skin. Nonpermeator by skin. Non-irritating to the eyes. Nonhazardous in case of ingestion. Non-hazardous in case of inhalation. Non-irritant for lungs. Non-sensitizer for lungs. Noncorrosive to the eyes. Non-corrosive for lungs (14).

8. Acetylsalicylic acid (aka Aspirin in pill form) •

Hazardous in case of skin contact (irritant), of eye contact (irritant). Slightly hazardous in case of skin contact (corrosive, permeator), of ingestion, of inhalation. Severe over-exposure can result in death (1).

III.

RESULTS: A. Week 1 Results-

NaOH and KHP Titration (Table 1) Trials

Amount of

Amount of KHP

Calculations

NaOH

in flask being

𝑀1 𝑉1 =𝑀2 𝑉2

Added mL

titrated mL

Final Molarity

1

20.8 mL

50 mL

(.05)(50)=𝑀2 (20.8)

.12M

2

9 mL

20 mL

(.05)(20)=𝑀2 (9)

.11M

3

7.2 mL

20 mL

(.05)(20)=𝑀2 (7.2)

.13M

Avg.

-

-

-

.12M

Molarity

NaOH and HCL Titration (Table 2) Trials

Amount of

Amount of HCL

Calculations

NaOH

in flask being

𝑀1 𝑉1 =𝑀2 𝑉2

Added mL

titrated mL

Final Molarity

1

13 mL

20 mL

(.12)(13)=𝑀2 (20)

.078M

2

17.5 mL

20 mL

(.12)(17.5)=𝑀2 (20)

.105M

3

18 mL

20 mL

(.12)(18)=𝑀2 (20)

.108M

Avg.

-

-

-

.097M

Molarity

B. Week 2 ResultsBaking Soda Solution and HCL Solution Titration (Table 3) Trials

Amount of

Amount of Baking

Calculations

HCL Added

Soda Solution in

𝑀1 𝑉1 =𝑀2 𝑉2

mL

beaker being

Final Molarity

titrated mL 1

5 mL

10 mL

(.097)(10)=𝑀2 (5)

.194 M

2

9.5 mL

10 mL

(.097)(10)=𝑀2 (9.5)

.102 M

3

11.5 mL

10 mL

(.097)(10)=𝑀2 (11.5)

.084 M

Avg.

-

-

-

.126 M

Final Molarity

Molarity

Aspirin Solution and NaOH Solution Titration (Table 4) Trials

Amount of

Amount of

Calculations

NaOH

Aspirin Solution

𝑀1 𝑉1 =𝑀2 𝑉2

Added mL

in beaker being titrated mL

1

6.2 mL

5 mL

(.12)(5)=𝑀2 (6.2)

.1 M

2

5.7 mL

5 mL

(.12)(5)=𝑀2 (5.7)

.09 M

3

5 mL

2.5 mL

(.12)(2.5)=𝑀2 (5)

.06 M

Avg.

-

-

-

.08 M

Molarity

Calculations: The main equation used for all the concentration calculations was 𝑀1 𝑉1 =𝑀2 𝑉2 . This equation was used to determine all the concentrations in each trial of each titration. We can use Table 4

Trial 1 as an example, we titrated the aspirin solution with the NaOH standardized solution to determine the concentration of the aspirin solution. So, we began with 5 mL of the aspirin solution in a beaker and added 6.2 mL of the NaOH solution to it and our theoretical concentration was .12M. So 𝑀1 is .12M, 𝑉1 is 5 mL, and 𝑉2 is 6.2M. If we plug this into the formula it would be (.12)(5)=𝑀2 (6.2), solve this and you get .1M. Another form of calculations we used was to average the concentrations. So, this would be done by adding the final concentration of each trial and dividing by 3(the number of trials). An example would be 2+4+6= 12/3= 4, in this case 4 would be the average. The last form of calculations we used was stoichiometry and volume calculation. This was used to discover how much water to mix with the product to form a solution. So, an example would be the aspirin solution. On the bottle of aspirin .325g of active ingredients was listed, we first had to switch g to mols using aspirins molar mass which could be done like this .325g × volume using the equation

𝑚𝑜𝑙𝑠 𝐶𝑜𝑛𝑐𝑒𝑛𝑡𝑟𝑎𝑡𝑖𝑜𝑛

1 𝑚𝑜𝑙 180𝑔

= .0018mols. Then we must calculate

= volume, so it would be written like this

.018L. Then lastly, we had to switch from L to mL, 018L×

1000𝑚𝐿 1𝐿

.0018 𝑚𝑜𝑙 .1𝑀

=

= 18 mL. So, from all these

calculations we determined that 18 mL of water is needed to mix with the .38g of aspirin.

I.

DISCUSSION: During week 1, the NaOH, HCL, and KHP solutions were standardized using the titration

method. The KHP was already standardized and was used to standardize the NaOH, and then the NaOH solution was used to standardize the HCL. The results from Table 1 displays the data from each trial and the concentration calculated using the data. Once three trials were performed an average concentration was determined, which came out to be .12M. This tells us that the average concentration of our NaOH solution is .12M, we can then use this number in the next part of the experiment to calculate the concentration of the HCL solution in each trial. As previously said, the next step in the experiment was to standardize the HCL solution. The results from Table 2 shows the data received and the concentration calculated using the data. So, like Table 1, Table 2 shows the average concentration of our HCL solution which was .097M, we can then use this number as our theoretical concentration for week 2 analysis to calculate the concentration of the baking soda. It is very important that we standardize the solutions first

because it helps us determine an accurate concentration and prevent any errors in the experiment and in future calculations. During week 2, we brought in aspirin as our household product to perform a quality check. Since aspirin is acidic, we had to use baking soda as the second item to use to perform a titration. Like the first week, we performed two titrations to record data. After recording data, we can then plug in the numbers into the equation, 𝑀1 𝑉1 =𝑀2 𝑉2 , to calculate the concentration of baking soda and aspirin. As can be seen from Table 3, the average concentration of the baking soda, in the titration between baking soda and HCL solution, was .126M. This number is approx. .023M higher than our theoretical concentration. For the next portion, we titrated the aspirin solution with NaOH solution, and determined the average concentration for the aspirin solution to be .083M. For this part of the experiment, in the equation the theoretical concentration is going to .12M, which is the average concentration of the NaOH solution calculated in Table 1. There were a few errors that occurred during the experiment. The first one was when we first made the aspirin solution, when the aspirin was mixed into the water about only half of the aspirin actually dissolved and got incorporated into the solution (which meant that aspirin was only partially soluble in room temp. water). This became a problem when we did trial one of the titration between the aspirin solution and NaOH solution because the calculated concentration was way off the theoretical concentration. So, to fix this problem we heated the aspirin solution, on a hot plate, to a boiling point to be able to fully incorporate the aspirin into the water. Another error that occurred in this experiment, was when we remade the aspirin solution to heat on the hot plate, there wasn’t enough solution to do three trials with 5ml/trial. However, we didn’t realize this until we reached the third and final trial, we then had to use 2.5ml to be titrated and reconfigure the data in the equation. There are a few things that would be changed if this experiment was to be done again. The first thing to change would be to try to keep each trial more consistent because the way we kept changing volumes, the indicators, and the amount of indicator in each trial may have affected the calculated concentration. Also, when we measured water for solutions rather than using more accurate glassware, like a graduated cylinder, we used a beaker which affected the solutions volume.

II.

CONCLUSION:

The original hypothesis for this experiment was to be able to conduct quality control on commercial products by doing quantitative tests to determine the accuracy of its concentrations. The hypothesis was proven correct, by performing acid-base titrations and calculating concentrations, we were able to discover the molarity of each commercial product. As mentioned in the discussion, a few errors occurred during the experiment, one was when the aspirin was mixed into the water it did not completely dissolve which made the calculated concentration for that trial really high. Another error that occurred was we didn’t make enough aspirin solution to create consistent trials, which may have interfered with the average concentration.

III.

RESEARCH CONNECTION: A group of researchers tested the food label accuracy of 24 common snacks from the US.

These snacks ranged from chips to chocolate to nuts and to yogurts. The label accuracy of the snacks was tested for energy and macronutrient content, which is fat, protein and carbohydrates, of “prepackaged energy-dense snack food products” (9). Of the 24 snacks, only 10 were used to determine the macronutrient content but all 24 were used to measure caloric content. Their methods on how to extract data included using a bomb calorimetry and food factors to estimate energy content. To determine the macronutrient content (according to Official Methods of Analysis), Numbered, dried and frozen pellets of each snack were sent to a lab. “Fat content was quantified by acid hydrolysis..., protein quantification was accomplished by multiplying the amount of nitrogen in the sample by 6.25 [and] carbohydrate content was calculated as total weight subtracting weight of fat, protein, moisture and ash” (9). As for the results, caloric content is higher than stated on the nutrition labels, metabolizable calories were found to be 4.3% higher than the label statement and carbohydrate content exceeded label statements by 7.7%, however fat and protein content were not significantly different from label statements. The FDA allows food labels to go over accurate facts by 20%, so all the data determined in this study were well within range. The motivation for this experiment was directed from different studies, including a national study that “demonstrated that the ubiquity of energy-dense snack foods was alarmingly high in retail stores throughout the U.S” (9). Since snacking has become a common and daily event, it is thought to be believed that the food labels are inaccurate which is affecting peoples weight loss/w...