The pH Cabbage Color Lab

The pH Cabbage Color Lab

By: Brady Pauken 

Overview:

       Using cabbage juice, in this lab we created a color spectrum using different pH levels in the juice. We used a controlled variable which was just untouched cabbage juice, which has a pH of 7. It is the color purple. We then added HCL and NaOH to the cabbage juice. This changed the pH of the juice, which also changes its color. 

Picture:

The test tube labeled "Our Own Experiment" was a mixture of around 10 drops of both acid and base, but perhaps a bit more base because it is a similar color to the bases.

Data Table:

This is a Data Table for each of the Test Tubes (Note that test tube 1 is on the right, and follows order from right to left(except for the "Our own experiment" tube))

 Graph:

This is the graph of the # of drops put into the juice as the x axis, and the pH as the y axis. I did this because the pH depends on the # of drops put into the juice. As you add more acid, the graph declines, but as you add more base, the graph inclines.

Questions:

#4 -  Which drops (acid or base) caused a more dramatic change in the pH of the solution? Why?

             

             I think that the bases caused a more dramatic change in the pH of the solution. I believe this because of the color change. If you think about it, changing from purple to red is not difficult, as you would just take away the color blue and would be left with red. However, to get from purple to yellow or green, is a more drastic change. In order for this to be accomplished, a more extreme chemical change would have to occur. Due to this, I believe that adding drops of base to the juice would have a more dramatic change in the pH of the solution.

#5 -  What did you learn?

             By completing this experiment, I learned about acids and bases, along with how they affect pH levels. The pH level of a substance can be swayed in either direction by simply adding acid or base to the solution. If you add more of each acid or base, then it will affect the pH level even more. Also, if you add color into the equation, things get more interesting. The starting color of a juice with a pH of 7 is purple. I learned that if I add more of an acid or base to the substance, it will in turn stray from the color purple more. For example, if i were to only add 1 drop of HCl to the juice, it would not change colors as much as if I added 10 drops.