Chemistry is the Only Way: February 2013

Sunday, February 10, 2013

Lab Session 22/01/13: Redox Reactions

Objective: To calculate the amount of potassium permanganate we could dissolve in hydrogen oxide.

Materials we used for the experiment:
- Potassium permanganate (KMnO₄) - Erlenmeyer flask
- Little cup - Pipette
- Burette - Hydrogen oxide
- Sulfuric acid 2M - Stand
- Clamp - Test tubes
- Test tube rack

Explanation

1) We first set up everything in place and then poured the Potassium permanganate in to the Burette until it was filled completely.

2) We then placed 4 mL of H₂O₂ in the Erlenmeyer flask along with 4 moles of Sulfuric acid and mixed it together.

3) We placed the Erlenmeyer flask underneath the Burette to start the titration.

4) We dissolved the Potassium permanganate until it came to a point that the substance in the Erlenmeyer flask started to change color. We came to a result that around 22 mL were dissolved therefore meaning that 28 mL were left in the Burette.

Results
- 50 mL of KMnO₄ in Burette
- 4 mL of H₂O₂ + 4M of HSO₄ in Erlenmeyer flask

50 mL of KMnO₄ – 22 mL = 28 mL of KMnO₄ left

Conclusion

We can conclude that the final result of the titration gives us a redox reaction. This means that one substance is reducing while the other is oxidizing. We stopped adding the Potassium permanganate once it started turning another color. We came up with a reddish brown color in the end.

Lab Session 05/02/13: Polimeter experiment

Objective: To obtain data from the polimeter (measurement of the conductivity) from two different elements in their own compounds. In this case we are using Tin (Sn) and Lead (Pb).

The list of substances we chose from:
- Fe²⁺/Fe
- Sn²⁺/Sn
- Cu²⁺/Cu
- Zn²⁺/Zn
- Pb²⁺/Pb
- Mg²⁺/Mg
- Ni²⁺/Ni

Materials we used for the experiment
- Tin (Sn) - Tin (II) chloride à SnCl₂ solution
- Lead (Pb) - Lead (II) nitrate à Pb(NO₃)₂ solution
- Polimeter - U-tube
- Cotton - Water
- Salt (NaCl)

Explanation
1)      We chose two different substances to perform the experiment. In our case, we chose Tin and Lead.
2)      We took the compounds of our substances which were SnCl₂ and Pb(NO₃)₂ and placed them in beakers.
3)      We then attached one end of the polimeters cable to one of the elements placed in their own aqueous compound solution and did it to the other.
4)      We put a bit of Sulfuric acid in the U shaped tube and then filled it up with water and placed cotton on the ends so it would not leak.
5)      We placed the U shaped tube in the beakers with the elements and their solutions and measures the conductivity at 2000m. It gave us a measurement of -51 to -49.

Results

Sn + SnCl₂

Pb + Pb(NO₃)₂

Shows a result of -51 to -49 at 2000m on the polimeter

Conclusion

We can conclude that the final result of the polimeter and what the conductivity of Tin in Tin solution and Lead in Lead solution is at -51 s/m (siemens/meter) to -49 s/m at 2000 m (meters). A conductivity meter or polimeter measures the ionic conductivity (or conversely, the resistance) of a liquid. The number it gives cannot directly be related to hardness, but rather, the total ion content of the liquid.