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pH determination attempts

First try​

To start, we needed values for different pH solution, we had:

  • 1 solution of HCl 18%
  • 1 solution of NaOH 1M
  • pH paper

From these we made 12 solutions from pH 1 to 10 (increase by one), 12 and 14. Then add 4ml of each solution in tanks and add 10 drops of red cabbage in each tank.

NB: from each initial solution we filled as many as possible tanks to obtain means of absorption. We obtained from 3 to 8 tanks for each pH.

If you want to see all these measures, please look at:

Second try​

Using the same stock solutions as before, and a pH-meter, we were able to make different solutions, with a precise pH. In each tank, we put 4 mL of acidic or basic solution and 5 drops of red cabbage solution. Plotting the absorbance in function of the pH, we obtained the following graph:

graph_red_cabbage.jpg

Here you can find the values we used:

Third try​

We made a new red cabbage solution, same concentration but this time with distilled water. In each tank we placed 4 ml of acidic or basic solution and again 5 drops of our re cabbage solution. Here is the plot od the absorbance in function of the pH:

graph_red_cabbage2.jpg

Here you can find the values we used: