Chemistry Eggshell Lab

Topics: Calcium carbonate, Titration, Hydrochloric acid Pages: 8 (2167 words) Published: January 28, 2013
Eggshell Lab

Lab Set-Up:

* pipette with pipette bulb
* conical flask
* 1 beaker
* 1 molar sodium hydroxide solution
* 2 molar hydrochloric acid solution
* 1 funnel
* 1 piece circular filter paper
* crushed poultry eggshell
* crushed farm eggshell
* phenolphthalein
* Distilled water
* White tile
* Paper tray
* burette in burette stand
* electronic scale

Step 1: Standardization of the NaOH solution using Standard 0.1M PHP 1. Take 10ml of the given NaOH solution and dilute with 90ml of water. Fill up the burette with this solution. Take 10ml of 0.1M potassium hydrogen phthalate (PHP) in the conical flask, add 1-2 drops of phenolphthalein and titrate with the diluted solution of the NaOH till the solution turns light pink. 2. Calculate the strength of the original NaOH solution.

Step 2: Poultry eggshell
1. Carefully weigh (1.5- 2.5g) crushed country eggshell in a paper tray using an electronic scale. 2. Take (60 ml-80ml) of HCl and dissolve crushed eggshell in solution for eight to ten hours or until reaction between eggshell and acid is complete. 3. Rinse burette with NaOH solution and place in burette stand. 4. Rinse pipette with HCl.

5. Rinse conical flask with distilled water.
6. Filter acid and eggshell solution into beaker through funnel to remove unreacted HCl. (This step is necessary not for chemical reasons, but rather so that pieces of eggshell do not get stuck in the pipette during transfer of the HCl.) 7. Use a pipette to move the unreacted HCl solution into the conical flask. 8. Place two drops of phenolphthalein (color indicator) into the solution. 9. Fill burette to the zero mark with NaOH solution.

10. Place conical flask under the burette and begin adding drops of NaOH into the flask. 11. Continue this process until the solution turns light pink. At this point, the titration has reached its endpoint and the acidic solution has been neutralized.

Step 3: Farm eggshell
12. Follow all steps as per procedure for country eggshell. 13. After you have collected the raw data, process it and also state your conclusion, evaluation and suggestions for improvement.

Standardization of the NaOH solution using standard 0.1M PHP Amount of 0.1M PHP (milliliters)| Amount of NaOH (milliliters)| 10| 25.1|
10| 23.5|
10| 23.4|
KHC8H4O4 (aq) + NaOH (aq) KNaC8H4O4 (aq) + H2O (l)

Concentration of PHP= 0.1M
Volume of PHP= 10 ml ± 0.003 ml
Average volume of NaOH= 24.03 ml ± 0.05 ml
The number of moles of PHP used 0.1 x 0.01= 1 x 10-3
Therefore the number of moles of NaOH used would also be 1 x 10-3 moles

This means that the concentration of NaOH is (1 x 10-3) / 24.03 = 4.16 x 10-5 gmol-1

However, the NaOH was diluted; 10 ml ± 0.003 ml was diluted with 90 ml ± 0.5 ml of water (The original concentration was 1.0M)

Raw data table:
Trial| Amount of NaOH used/cm±0.05|
1| 23.5|
2| 23.5|
3| 23.4|
Mass of eggshell: 2.213±0.001 g
Volume of HCl used: 10±0.05 cm3 (taken from 70.0±0.05 cm3 that was reacted with eggshell) Conc of HCl: 2.0 moldm-3
As the NaOH was being poured, via burette, into the conical flask, the solution turned slightly pink, although it went back to colorless after stirring the solution. But when 23.5, 23.5, and 23.4 cm of NaOH was poured in, for each trial respectively, the whole solution turned light pink. Data processing:

Reaction: 2HCl+NaOH 2NaCl+H2O
Initial moles of HCl= concentration x volume
= 2 mol dm-3 x 0.056 dm-3 = 0.112 moles of HCl
Amount of 1 molar NaOH required to neutralize the HCl= 13.5 ml. Therefore, the number of moles of 1 molar NaOH required to neutralize the HCl = concentration x volume = 1 mol dm-3 x 0.0135 dm3...
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