Winter Ice Melt Palooza!

Learn why salt helps to melt ice using different types of salt. 


Appropriate Age Level

5+ (some concepts can be 3+)

Science Learned
Freezing Point - The temperature at which a liquid becomes a solid
Temperature - a physical measurement of the hotness or coolness of something
Freezing Point depression - when the freezing point of something is lowered by a solute
Colligative Property - a property of a substance that depends on the number of particles present instead of type of particle.
Solution - a homogeneous mixture of solute and solvent that is in one phase (liquid, solid, gas)
Solvent - A substance that dissolves a solute.
Solute - A substance, usually a solid, dissolved into another substance, usually a liquid. 
Liquid- a state of matter that is characterized by taking up a definite volume but having no particular shape
Solid - state of matter that is characterized by being structurally rigid and resistance to change

Materials Needed
Essential:
Ice Block
Table Salt - NaCl
Optional:
Magnesium Chloride MgCl2
Calcium Chloride CaCl2
Thermometer

Experiment
1. Either find a block of ice outside, or freeze some water in a plastic container. 

2. Explain how ice is frozen water and a solid and how its freezing point is at 32F or 0C.  When water is not frozen it is in the liquid state. 

3. On a surface that you don't mind getting wet, take some table salt and add it to the block of ice in one area. Attempt to stir in the salt into the ice.  Notice how the salt, the solute, melts the ice, the solvent. It essentially lowers its freezing point of the ice.  (If the student wants to know more, it essentially breaks the hydrogen bonds required to keep the ice in solid form by the salt molecules coming in and wanting to share the same space and transferring electrons.)

4. If you have Magnesium Chloride and/or Calcium Chloride on hand you can add a spoonful of each to other parts of the block.  (You could probably add some different food colorings to differentiate the different materials if you would like more wow!) If you have a thermometer on hand you can check out the differences in temperature of the solution melts.  The MgCl2 will depress the freezing point of ice to 5F.  While table salt only depresses it until 15F. Calcium chloride depresses it until -20F. While if you are doing this experiment inside the temperatures gotten will not be at these exact levels you should be able to see some difference. 

5.  Explain that the differences of the freezing points arrise from freezing point depression being a colligative property and the differences in size of the molecules, where NaCl is the smallest, CaCl2 is the largest, makes a difference in melt points. 

Time Allotted
20 minutes

References
http://chemistry.about.com/od/solutionsmixtures/a/freezingpointde.-Nxc.htm
http://chemistry.about.com/od/howthingsworkfaqs/f/how-does-salt-melt-ice.htm
http://en.wikipedia.org/wiki/Colligative_properties

Grow tomatoes, grow!

 Grow some tomato plants to later plant outside and learn about germination and photosynthesis in the process.

Appropriate Age Level

3+ for the actual experiment

5+ for concepts


Materials Needed
Dirt
Planting pot(s) or plastic cups
Tomato seeds
Water
Time
Camera to take growth pictures with

Science Concepts Learned

Germination (1) - (see picture below) the process where a seed grows to become a seedling. For a seed to do this it needs water, oxygen and to be at certain temperature. 

1.The root emerges through the seed.

2.The part of the seed called the hypocotyl pushes it way out of the soil.

3.The hypocotyl straightens itself out.

4.Leaves begin to form.


Photosynthesis -  (see photo below) the process where plants convert energy from light from the sun into chemical energy that can be used by the plant.  

The reaction is the following (3):

                                light

carbon dioxide + water  ------->    sugar + oxygen 


Activity/Experiment

1. Set out cups or pots and fill the pots with dirt (a starter mix for plants is recommended) as many as you want though think about seed crowding.  

2. Plant tomato seeds 1/4 inch deep in the dirt (2).

3. Water the seed/dirt mixture to make it soggy but not swampy.

4. In 5 to 10 days germination should occur. Take a picture of the potted seeds each day in this range and discuss the germination steps listed above in the terms section. 

5. After germination has occurred, weekly take pictures of the plants.  

6. After a few weeks compare the size of the plants with the pictures taken and from them you can talk about photosynthesis and how the light and water has helped the plant to grow. 

7. Continue growing the plants, and you can either transfer them to larger pots and keep them inside or you can transfer them outside if it is the right time of year. 

8. Enjoy the fruit you get from this practical example of science!


Time Allotted 

5-10 minutes weekly

References: 

1. http://www.cactus-art.biz/note-book/Dictionary/Dictionary_G/dictionary_germination.htm
2. http://www.colostate.edu/Depts/CoopExt/4DMG/VegFruit/tomatind.htm
3. http://en.wikipedia.org/wiki/Photosynthesis

Cleaning Reaction: Acid Base Chemistry

Appropriate Age Level
3+ (more depth for older children) 

Science Concepts Learned

Acid Base Reaction - a neutralization reaction where enough base is added to an acid to neutralize it into a salt and water

The following acid base reactions occur when vinegar(CH3COOH) and baking soda(NaHCO3) react:

A. CH3COOH + NaHCO3 ===> NaCH₃COO + H2CO3
      (vinegar)    (baking soda)  (sodium acetate)  (carbonic acid) 
B. H2CO3 ===> CO2 + H2O
(carbonic acid)  (carbon dioxide) (water)
Overall:  CH3COOH + NaHCO3 ===> NaCH3COO + CO2 + H2O
                (vinegar)    (baking soda)  (sodium acetate) (carbon dioxide) (water)

Compound Reaction - reaction where there are intermediates that are not in the products or reactants

Decomposition Reaction -  separation of a chemical compounds into elements or simpler compounds

Exothermic Reaction - a chemical reaction where energy is released in the form of heat or light.   

Materials Needed

1/2 cup White Vinegar
1/2 cup Baking Soda
two containers for each substance
optional: liquid measuring cup


Activity/Experiment

1. Pour 1/2 cup of vinegar into a container, one with a lid for smaller children.  Measure out 1/2 cup of baking soda and put into another container. 

2. Now, this is your choice.  You can either carry out the experiment this in a bowl or on a spot that needs some cleaning. For more containment use the bowl, but if you want something cleaned along with science being learned then by all means be creative.

3. Add a tablespoon of the baking soda to the container or designated spot.  Spread it around evenly.  Add a tablespoon of vinegar on top of the baking soda and watch it react.

4. Rinse out and dry the container, or choose a different spot to clean and repeat, this time explaining the reaction happening :


A. CH3COOH + NaHCO3 ===> NaCH₃COO + H2CO3
      (vinegar)    (baking soda)  (sodium acetate)  (carbonic acid) 
B. H2CO3 ===> CO2 + H2O
(carbonic acid)  (carbon dioxide) (water)
Overall:  CH3COOH + NaHCO3 ===> NaCH3COO + CO2 + H2O
                (vinegar)    (baking soda)  (sodium acetate) (carbon dioxide) (water)

5. Depending on the age of the student you can go into as much detail as you want, you can add in the stoichiometry with the associated compounds, you can explain how this is a compound reaction versus a one-step reaction, you can explain how this is a decomposition reaction and go into detail about what an acid and a base means.

Time Allotted 
10-15 minutes

Singing and Dancing Bones

Appropriate Age Level

7+

Science Concepts Learned

The names of the bones of the body using a song. You can teach as many bone names as you want, all 206 if wanted. 

Here are all the bones:

Activity/Experiment

The run down of this activity is to put the names of the bones that you want your child to learn into a song, with them making up the song as you go.  Kids learn well through song, so why not learn some biology in the meantime. 

Here is an example of a bone song, that comes from the ever popular Hannah Montana.  You can learn 30 or so bones from it.

Doin' the Bone Dance

When I milk the cow
On uncle earl's farm
I use the ulna bone
That is in my arm

Moo-Yah! 

Everybody knows the bones
Just had to find a way
Everybody know what I'm talking 'bout
That's how I'll get an A

My body's many parts
And this is where it starts
Phalanges I have 10
And Metatarsals then

I got some Tarsals too
I'll put them in my shoe
The Fibula is next
According to my text

Then comes the Tibia
That ain't no Fibia

And now up to my knee
Yeah, yeah, yeah
That's the patella to me

Chorus:
We're doing the bone dance
You study the answers
Again and again til I get it right

We're doing the bone dance
You dance and you learn it
And we won't mess up this test
We'll get it perfect

And now I take it home
With the Parietal bone
It might be crazy
But we learn that way

Temporal and frontal too
And now we're finally through
That makes two hundred & six
I found a way that clicks

Chant: Bone Thugs in the house

We're doing the bone dance
You study the answers
Again and again till I get it right

We're doing the bone dance
You dance and you learn it
And we won't mess up this test
We'll get it perfect... word!

Time Allotted 

~ 30 minutes

Your Bedroom Door and Torque

Appropriate Age Level
5+ (math for older children 10+ , concepts for younger children 5-9)

Science Concepts Learned

Torque (τ) : the ability for an object to rotate around (spin around) an axis when a force (a push) is applied.

τ= rFsinφ
r=radius (m) (probably will be measuring in cm and will have to convert)
F=Force (N)
φ = angle of rotation 

Materials Needed

Hinged Door
Protractor

Activity/Experiment

1. Explain that a door has torque, and that the hinges are its axes. 

2. Have the child pick 3 different distances, about the same distance apart at the middle of the door.

3. Have the child push the door with the same strength at each distance/radius. (If you are doing the math portion of this experiment, measure each radius from the end of the door and assign 1N for the arbitrary amount of force being used.)

4. Discuss how it was easier to push the door further away from the hinges than closer because it has more torque due to the radius being longer, and that it was harder closer to the hinges because it has less torque.  (If doing the math part here, plug in the numbers, and also use a protractor to see the angle associated with the movement, place the protractor at the end of the door where the hinges are to get the most accurate measurement. The protractor should have one side where the door started and the other where the door ended when pushed.) 

5. Now have the child push the door with 3 different strengths at the same point in the door.  (Measure angles again with the protractor, and use 1, 2, and 3 N as the force increases smallest push to biggest push)

6. Discuss how the differences in pushes made the door swing different amounts, the smallest push was the smallest force and therefore had the least amount of torque etc.

7. And there you have it torque!

Time Allotted 

15-30 depending on how quickly the math is carried out

Physics for Scientists and Engineers 5th Ed. 2000

Oatmeal Raisin vs. Sugar Cookies, A Case of Mixtures

Appropriate Age Level

3 +

Science Concepts Learned

Mixture - variable composition; meaning it consists of different things

Homogeneous - visibly indistinguishable parts; everything blends together

Heterogeneous - visibly distinguishable parts; you can pick out different pieces of the mixture

Chemical change - a given substance becomes a new substance or substances with different properties and composition; the components went through a change and can no longer return to its original state.

Activity/Experiment

1. Find two recipes or cookie mixes, one for oatmeal raisin and the other for sugar cookies.

2. First get out all the ingredients for the sugar cookies and talk about all the different items being put together to form what is known as mixture.

3. Mix all components of the mixture together, adding according to the recipe directions.  While mixing and adding items, have the child look at the mixture to see if they can see the different parts of the mixture.

4. When the mixture gets to be smoothly mixed so that you can no longer make out individual components, declare it homogeneous and explain why.

5. Repeat steps 2-4 with the oatmeal raisin cookies.  However, this mixture will never be homogeneous and instead will be heterogeneous.  Explain to the child why its different and ask them what they can still see in the cookie batter that makes it heterogeneous.

6. Bake cookies according to directions.

7. I threw this one in for a bonus, but once baked you can explain to the child that the cookies went through a chemical change, they no longer can be batter anymore, but are cooked and changed chemically. (You honestly can leave this experiment with just the mixtures part, but I thought since it was there why not add it in)

Time Allotted 

15-30 minutes for mixing, follow baking instructions per mix.


References: Zumdahl Chemistry 5th Edition, 2000.