Anthocyanins


Anthocyanins are naturally occurring compounds found in red cabbage. When extracted and placed in solution, these compounds change colors dependent on the pH.
My Spectrum (5 points): Include a picture of your own red cabbage universal pH indicator


Acid and base concentration is measured on a logarithm scale known as the pH scale. Common values for pH range from 1-14.

pH strips like these can be placed in a solution and will change color to indicate a rough pH reading. Retrieve a strip of pH test paper and place a sample of your own saliva onto the strip.

1.) Collect a piece of pH paper.
2.) Place sample of saliva onto pH paper.
3.) Take photographic evidence of your test strip.
4.) Using the same device and lighting, get a picture of the color scale shown on the strip packaging. We need to keep our lighting consistent, so use the same camera!

My Test Strips (5 points): Include a picture of your own saliva stained pH paper


It looks green. That's a pH of 6. Or 7. Or 8. I don't know how green it is. Is there a more accurate way to measure this?

Colors can be measured in a number of ways, including RGB (left) or hexadecimal (right). Both correspond to a mixing of the primary colors (Red, Green, and Blue) to get to a final color as shown. Hexadecimal is used primarily in web design, while the RGB scale is used for most other software.



1.) Open your picture of your stained pH strip in Pixlr. (if the picture is in HEIC format, you need to convert it first using www.heictojpg.com)

2.) Select the colorpicker tool. Select at least 3 different spots within the saliva testing area to determine the average color. Double click the color panel (shown below) to get the hexadecimal code for your color. Here the hexadecimal code for one of the pixels selected in the testing area was #a3811a

My Colors: (3 points EC) Identify the 3 Hex codes for your own pH strip.

Example:
Color 1: a3811a
Color 2: a17f18
Color 3: a6841e



3.) Record at least 3 different hexadecimal colors from your test strip picture.

4a.) AVERAGE THE COLORS. Go to ColorBlender. Input your first and second color to find a midpoint color (as shown below). Repeat the step again with the midpoint color (#A28019 in this example) and your third color. 

 
4b.) 1+2 Midpoint + 3rd color blend = #A4821C

5.) Convert the color into RGB by hitting the RGB button:


6.) Do the same thing with the color code of your pH strip reference guide.


For this reference guide, pH 5 = #cfb525 (207, 138, 37)
For this reference guide, pH 6 = #bdbd39 (189, 189, 57)
For this reference guide, pH 7 = #5b9954 (92, 153, 84)
For this reference guide, pH 8 = #4f824d (79, 128, 77)

7.) Calculate the color distance between the pH seen in your saliva sample, and the pH reference guide.

Color Distance = √(Red of sample - Red of Guide)2 + (Blue of Sample - Blue of Guide)2 + (Green of Sample - Green of Guide)2

For our stained strip example seen above (164, 130, 28), we do the following calculations

D to pH 5 = (164 - 207)2 + (130 - 138)2 + (28 - 37)2 = 44.65
D to pH 6 = (164 - 189)2 + (130 - 189)2 + (28 - 57)2 = 78.9

Add the distances together 

D to pH 5/6 total = 44.65 + 78.9 = 123.55
Extrapolated pH = 5 + 44.65/123.55 = 5.36

My pH: (2 points EC) Identify the pH of your strip using the above steps using the distance formula. 
 
D to pH 5 = √(164 - 207)2 + (130 - 138)2 + (28 - 37)2 = 44.65
D to pH 6 = √(164 - 189)2 + (130 - 189)2 + (28 - 57)2 = 78.9
D to pH 5/6 total = 44.65 + 78.9 = 123.55
Extrapolated pH = 5 + 44.65/123.55 = 5.36
pH from strip = 5.36

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