Observation: When I was rinsing out my bowl of red cabbage soup the water turned green.

Step 1: Hypothesis: I believe the cabbage in the cabbage soup changes color to green when it comes in contact with certain other substances. I also believe there must have been traces of one of these substances in my water.

<p>i suggest using less baking soda in your cabbage soup next time you cook. ;-)</p>
we do this as a science experiment with kids: put a few cabbage leaves in a microwave safe bowl and nuke for a couple of minutes until juice starts appearing in the dish; fry an egg in the cabbage juice to get a green egg, serve with ham!
<p>The stock that comes from cooking a red cabbage can be used to tell if other substances are acidic or alkaline/base. When I was a kid I used to make litmus paper by soaking a neutral white paper in in red cabbage stock and then drying it. </p><p>My greatest memory of using it was when I used it to check the volcanic dust that had settled over everything after Mt. Saint Helens blew. The news kept saying it might be acidic and not to wash it off. I found that it was slightly alkaline. We washed off the cars and house.</p>
Thats really cool
<p>That was a very good demonstration of the scientific process. </p>
Thak you
<p>I wish I had you as a chemistry teacher.</p>
<p>Tap water is often treated with bleach as well as chlorine during the sanitation process.</p>
<p>The chlorine in water supplies is typically in the form of chloramine. It is more stable and takes longer to off-gas.</p>
That makes sense. Thanks for sharing!
<p>Here's some information if your interested regarding the disinfection process dealing with chlorine and it's off shoots</p><p><a href="http://water.epa.gov/drink/contaminants/basicinformation/disinfectants.cfm" rel="nofollow">http://water.epa.gov/drink/contaminants/basicinfor...</a></p>
<p>Commercial vinegars (like Heinz distilled white vinegar) are changed to have 5% acidity. But an interesting experiment!</p>
<p>I do this as an entry acid/base lab for Grade 10 students, but solution is not boiled. I put half a head of red cabbage, cut up in chunks into a blender and then add one cup of distilled water. Blend to a puree and strain the liquid off. We use round filter paper at school and soak it in the liquid for up to 10 minutes and then hang the filter paper in the fume hood to dry. I have also done this with my nephews and nieces using coffee filters and then hanging them to dry outside. Gets fairly smelly so I recommend the outdoor hanging. Once dry, filters can be either stored in Ziploc bags in the freezer or used right away. Students (or my kids) fold the paper in half, half again and then half again twice more -- makes 8 pie wedges. Label the circular edge with whatever substance you are testing the pH for, grab some droppers (have used plastic spoons in a pinch) and start adding your testers. Cheap way to introduce acid /base.</p>
Nice experiment. I've come across cabbage as a PH indicator in old chemistry books but never tried it myself. I think salt is considered not to have a PH which is why it wouldn't change the colour.
It would make sense that salt doesn't have a PH. Thanks for pointing this out.
<p>pH is actually a measure of the activity of a hydrogen ion, and salts do have an effect on this. </p>
On the spit and saliva front, they as substances tend to be near enough neutral which shows green on the pH scale(this is of course affected by what you eat and drink so not always).
Good to know.
Salt is neutral Ph. What you found is the original litmus test. Good work. Be sure to wash the cabbage if you eat it.
I'll take your word on salt being a neutral. It was very hard to tell salt and the two water samples. Even though I labled salt as a base it was almost exactly the same as the distlled water. Thanks for posting!
well done! i have an 8 yr old that is developing an interest in science and i am going to do this with her this weeks
Please do, and if you do don't skip the &quot;More Fun Before Cleaning Up.&quot; When I did it I showed it to my 8 year old brother and he got a real kick out of it!
You don't need to go through such hassle to create red cabbage ph indicator. No need to boil the water, just put your cabbage and water in a blender, liquify then strain and collect your indicator juice. The active ingredient (flavin an anthocyanin) is water soluble.
I didn't try blending the cabbage but it really doesn't take long too boil. I will try blending next time I do this. Thanks!
our 8 yr old and i will boil our cabbage... and then eat it:)
I must say. If you do this experiment, you have to do the last part. It looks really cool!!!
Nice job!
Thank you Kiteman.
<p>So, you have urine or saliva in your tapwater. Might wanna get a purification filter for that.</p>
Are you sure this means I have urine or saliva in my tap water? Shadowjfaith seems to have a more pleasant explanation. How would they get in my tap water anyways?
<p>The fact that red cabbage is a pH indicator is well known, but in any case I like your instructable: you set-up a clear experiment and proceed to conclusions.</p>
Thanks you.

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