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Water, the Magic Molecule – Lesson 6

For this lesson we are going to check in on a couple of our experiments and see what is happening – as well as explain some of it.

 

HOMEWORK ASSIGNMENT UPDATE

Some of you are participating in a homework assignment assigned back during lesson 1.  You have placed an inorganic substance (like sand, or a rock) in one glass of water.  In a second you have placed an organic one (like a leaf or a seed).  And in a third you have placed a man-made object (like a nail, or a coin).

          It has been six weeks now, has anything changed in either of them?  Are they dissolving yet?

Let’s discuss glass #2 – the organic.

In Lesson 3 we explained how water (the polar molecule) could (would) eventually dissolve compounds.  We explained that being a “magnet”, water could break apart compounds (which are connected by different charges).  I am not sure what you placed in your second jar – it could have been a leaf, a seed, something organic.

An acorn. Organic food for many creatures.
Photo: UF IFAS Pinellas Co.

 

We use the term organic pretty loosely these days, but what organic compounds are, are those made of (or produced from) living organisms.  They are based around the element carbon.  There is bone, blood, skin, shell, scales, leaves, seeds, roots, – everything that is part of life.  There are many organic compounds found in living things.  They are based on carbon but have other elements as well.  Hydrogen, oxygen, and nitrogen are also very common in organic compounds.  When you get older you can take a science course in organic chemistry and learn all about these.

 

So, what happened when I put an organic compound in water?

 

Well, what should have happened was that it did not dissolve – (if it did, I have a guess as to why, mor eon that at the end) – but let’s assume that it did not.

 

Why not?

Water dissolves everything right?

It is polar and can act like a magnet taking compounds apart – why not organic compounds?

 

The answer lies in that SOME organic compounds are insoluble (cannot be dissolved by water).  One of those are called lipids – what we call fats and oils.  You may have heard that OIL AND WATER DO NOT MIX… well in a sense, they do not.  Water cannot dissolve them.

 

Lipids are organic compounds made from carbon, oxygen, and hydrogen.  They are used by living creatures to store, and produce, energy they need to survive.  We always hear that “eating fat is bad for you” well, eating TOO much of certain fats is bad for you – this is true.  BUT we need fat in our diet.  It provides us some needed nutrients as well as energy – again, just not too much of the saturated fats.  You can see how much saturated fat is in your food by reading the labels – activity 😊  

The food pyramid.
Image: University of Florida

 

So, it is important for energy in life – but what about the seed in glass #2?

 

Turns out we find a lot of lipids (fats and oils) in our skin.  This is pretty cool really because you might remember from a previous lesson that most of our bodies are made of water.  If you look at our organs, they are made of tissues.  If you look at tissues, they are made of cells.  If you look at cells, they are mostly water.

 

If we are mostly water – and water dissolves everything – shouldn’t it dissolve our bodies?

Dissolve the cells, tissues, and organs?

Shouldn’t it dissolve us the way sand and rock are dissolved?

 

Yes… except, that the membrane surrounding the cell is made of lipids (fats and oils) and lipids DO NOT DISSOLVE IN WATER – they are insoluble in water.

For this reason, we do not dissolve. Nor does a leaf, seed, or any other organic compound you may have placed in glass #2 because our “skin” is made of compounds that are insoluble.

There are many other compounds that are insoluble in water – activity.  You will learn when you take chemistry later in life, why they are.

 

NOW… WHAT IF YOUR ORGANIC COMPOUND DISSOLVED IN THIS EXPERIMENT?

 

First, are you sure you placed an organic compound in there?  I am assuming you did.

Second, if you place an apple or dead fish into the water by the beach – what happens?

It APPEARS to dissolve – or “rots”.

But actually, it is not – it is being eaten.

Dead fish washed up on Florida beaches during an outbreak of red tide along the Gulf Coast
Photo: USF

 

When living things (or parts of living things) – like apples, fish, and seeds die (or fall from the tree) they still possess all of the organic compounds (lipids, sugars, etc.) that it had in its body when it died (fell).  This is food for other creatures.  This is WHY we eat is to resupply our bodies with needed organic compounds.

 

Think about it, you do not eat sand or rock.  You eat plants and animals (or parts of them).  Some people only eat plants – which is fine – but they have to make sure they are eating a mixture of plants so that they can obtain the nutrients they miss by not eating animals – and they do.

Wild turkeys feeding on acorns that have fallen.
Photo: Shep Eubanks UF

 

So, when a seed or fruit falls – it is food.  Squirrels, deer, birds, LOTS of creatures seek these out.  Some creatures consume dead animals – the organic compounds are still there.  We call these scavengers and they are an important member of the community.  For without them, dead creatures would still be around.  We think of eating a dead animal on the side of the road, or a dead fish at the bottom of a lake, as pretty gross – and it can make us sick – we ARE NOT scavengers in that sense.  But there are creatures that are very good at it and we are glad they are there to help “clean-up” the environment.

 

Some bacteria are like this.  They like to consume food lying on the ground.  As we watch a dead fish (or a seed in glass #2) dissolve – we are actually watching it “rot” – which is actually watching bacteria consume it.  So, if your organic compound did “dissolve”, it did not really – it “rotted” – it is being consumed by bacteria – probably time to get rid of this one!  😊

 

Okay – that was a lot for today.  Let’s do an activity!

 

ACTIVITY

          Let’s start by looking in your refrigerator and your pantry for foods that have labels.  Which ones have fats?  Which ones have a lot of fat?  It will tell you how much saturated and unsaturated fat the food has.  Unsaturated fat is good for you – you do not want a lot of saturated fat.  The label also tells you what percent of your total daily intake of unsaturated (and saturated) fat one serving of this food will provide.  This helps you to not eat too much of it.  Which foods have a lot of saturated fats?  It is okay to eat those (again, you need some) – just not too much.   

          Search for lipids on the internet.  Look at the images of what the compounds look like.  Many are crooked lines and circles.  They are pretty cool looking.  Draw a couple of them on paper.  I think the different ones are kind of neat to look at and draw. 

          Search for “compounds insoluble in water” to see what other compounds (besides – lipids/fats) are insoluble.  There are quite a few.

          NOW let’s do another experiment.  

          Find some liquid products in your refrigerator (get parents’ permission please 😊).  Things like chocolate syrup, maple syrup, hot sauce, salad dressing, milk, orange juice, HOW KNOWS WHAT YOU HAVE. 

          Check the label (if they have one) and see how much saturated and/or unsaturated fat the product has. 

          BEING FAT, DO YOU THINK IT WILL “DISSOLVE” IN WATER? Let see.  Pour a glass of water and then pour a small amount of your liquid into the glass and stir.  WHAT HAPPENED? 

I HOPE, WITH THESE LESSONS, YOU ARE BETTER UNDERSTANDING THE MAGIC MOLECULE WE CALL WATER. 

I HOPE YOU ALL ARE DOING WELL

HAVE FUN AND STAY SAFE.