Osmosis demonstration using eggs

Remember this? Today we are going t need 2 of those, maybe more if you want to go a little further.
Today we are going to play and learn about osmosis.

Before continuing:
Cells have several transport mechanisms, in other words, several different ways to make the molecules to pass from inside to outside and vice versa. On of those mechanisms is called osmosis, and we can say for sure "that's all about concentration".

Osmosis is the movement of solvent molecules through a membrane from a region of  lower solute  concentration, to a region of higher concentration.
In other words, and considering the solvent is water, osmosis is the movement of water molecules from "in" or "out" the cell, aiming to match the concentration on both sides of the membrane.

In general we only can see a cell with a microscope. You don’t need a super microscope like electronic, a optical is enough.

In Nature there is a group of cells witch don't need a microscope to be "seen”, the eggs of species that "lay eggs." Ostrich eggs are the biggest eggs (not extinct specie), humming birds are the smallest, to "make" one ostrich egg we need 24 chicken eggs.

The egg is a cell, full of potential, to become a new being; only our frying pan or a starving predator can stop it from happen.
This cell have, like any other cell, a membrane (works as envelope for white and yolk), this membrane is double layered and is easy to observe on the blunt region where it forms a air pouch.

Let's start our demonstration. Before anything else we need to "undress" 2 eggs, you can see how here.

Ready?
Let’s go

What we need

• 2 jars with lid, big enough to place the egg inside,
• marker, to write on glass,
• water,
• 2 naked eggs,
• honey.

How to:

1. Put a "naked egg" in each jar;
2. Fill the first with water;
3. Fill the second with honey;
4. Close the two jars;
5. Label them with the marker, write on the first "H2O" or "water" and in the second "honey";
6. Place the jars in the refrigerator;
7. Wait 24 hours;
8. Take the eggs of the jars.
9. What do you see?

Observations:
The egg in the water jar looks like swollen and smooth.
The egg in the honey jar looks like wrinkled.

Why?
The white part of the egg has 90% water and the honey has only about 18%. We placed our cell (the egg) in two different environments, the water (with 100% water molecules, or close enough) and the honey (with about 18% H2O).

In the first case the water flow goes from a 100% environment to a 90% environment, from the water to the cell (egg), theoretically until the two concentrations are set at 95%, the egg swells.
In the second jar the water flows from the 90% environment to the 18% environment, from the cell to the water, theoretically until the two concentrations are set at 54%, the egg wrinkles.

At this process, where solvent molecules move (in this example H2O) to find a equilibrium concentration, in two different environments, separated by a membrane, we call osmosis.

Image:

• |X| here the outside H2O concentration match the inside concentration;
• |>X| here the concentration outside the cell/egg membrane is lower then the concentration inside it, the honey example.
• |<X| here the concentration outside the cell/egg membrane is higher then the concentration inside it, the water flask example;

Make this an experiment
Try other variables; remember to write down all your observations:

• Use water with food coloring;
• Use alcohol;
• Use salt water;
• Use Vinegar;
• Or simply, place your "honey naked egg" in a jar with water and wait another 24h, what do you think it will happen?

Sources:
http://www.victorialodging.com/recreation/birding/small-big-fast-slow
http://fisiologia.med.up.pt/Textos_Apoio/Membranas/Membranas.pdf
http://www.benefits-of-honey.com/honey-nutrition.html
Et voilá!
Play with eggs, learn from them

Enjoy!

Naked egg

Another science experiment with eggs.
With this demonstration we will be able to see the egg yolk, without break the egg shell.

All the eggs have 2 major parts, the yolk and the white. Both this parts are essential to the egg and protected by a thin membrane. This is a double membrane and is easily observed on the flattened part of the egg, here assumes the form of a air bag.

What we are going to do it's simple, we are going to discard from the equation the egg shell, leaving intact the membrane and everything inside.

This essay takes about one week, all depends on the type of acetic acid we use and on the size of the egg.

We will need:

• vinegar, the flat one, with no flavors will work the best,
• glass jar with lid, big enough "to drawn" the egg inside,
• Raw egg.

How to: 

1. Place the egg in the jar;  
2. Cover the egg with the vinegar;
3. Close the jar, tight, to avoid the vinegar to split and the odor to spreading;
4. Store the jar in a cool and safe place, a kitchen cabinet for example;
5. Wait 24 hours;
6. Replace the vinegar with careful, reject the vinegar inside, and replace it with fresh vinegar;
7. Store it again;
8. Wait 6 more days, replace the vinegar each 2 days, tic tac tic tac;
9. Remove the egg from the inside of the jar very carefully, reject the vinegar;
10. Wash the egg with running water, very carefully, the membrane can burst.

Results:
Tell your restless to record everything he/she see/observe.

You can show him/her the jar every 24h so he can see/register the demonstration evolution. This simple gesture stimulates the observation and helps the child to think and ask.

The egg shell is made of calcium carbonate. The chemical reaction between the acetic acid (vinegar) and the egg shell (calcium carbonate), makes the second disappear, in this process bubbling and carbon dioxide are formed. The raw egg remains intact due to the thin transparent exterior membrane.

Try this, and transform the demonstration in a experiment:

• What happens if you place the naked egg against the light? 
• Drop the naked egg from 2in height... not more... in a smooth surface, what happen?
• On the same day you place the raw egg in vinegar, use other options, in different jars:
• use a boiled egg instead;
• use a boiled egg but with no shell;
• After the 7 days what are the major differences between all eggs?

Et Voilá!
A jumpy naked egg

Enjoy!

Spinning egg, to distinguish between a raw and a boiled egg- Newton First Law

How to distinguish between a raw and a boiled egg?


We will need:

• 2 eggs,
• smooth surface. 

How to:

1. Boil one of the eggs;
2. Let cool;
3. Give both eggs to the restless kid, and ask him/her witch one is boiled; 
4. Ask your child to spin both eggs on the smooth surface. 

What happened?
 One of the eggs spin continuously, the other one oscillates randomly.
The egg spinning continuously is the boiled egg, the other one is the raw.
 
Why?
 The boiled egg is solid, the raw is liquid.When you spin the raw egg the liquid spins inside, but takes a few seconds to overcome the inertia and therefore the movement is not continuous.
The boiled egg is solid  and therefore the inside moves with the shell.

This is Newton First Law of Movement:

 
"All bodies remain in their state of rest or uniform rectilinear motion, unless they are forced to change its state by influence of external forces"
In simpler terms, the Newton's First Law says: "If something is moving or stopped, will remain in motion or stopped unless something disturbs the system."

You can do another test:
Spin the raw egg, when the egg is spinning continuously place your finger on top of it, to stop it, and take it fast. You will see that the raw egg still moving after you stop the shell... why? Because the liquid inside remains in motion.


Et Voilá!

Newton in action!

Enjoy!

Egg in a bottle

Eggs are in the class of funny food, we can do amazing tests/experiences with them. Despite being food, and "we shouldn't play with food" once in a live time will not make great damage. The challenge is quite simple, place a peeled boiled egg in a bottle without breaking it.

This need adult supervision

What we need:

• glass bottle,
• matches,
• medium boiled egg.

How to:

• Boil the egg. It should be well cooked;
• Take several matches; like 6 or 7;
• Light them and as fast as you can place them inside the bottle;
• Immediately put the egg on the bottleneck.

You must be very fast,  its normal if you can't succeed at the first time. Keep trying!

What happen:
The egg is sucked into the bottle.

Why?
Before we place the matches in the bottle, the air inside and outside the bottle were at same pressure and temperature. What we did was light the matches and place them inside the bottle, then fast and quickly we sealed the bottleneck with the boiled egg, this will make the air inside the bottle to expand and heat. After a few moments (depends on the bottle size) the fire extinguish (because all the O2 is finally consumed), the air in the bottle cools and contracts, and now the pressure inside the bottle is lower then the pressure outside, and respecting the laws of physics, pressure outside "pushes" the egg into the bottle.

Et Voilá!
It's magic.
As an alternative to hard-boiled egg, use a balloon filled like an egg.

Enjoy!