Chemistry Unit- Lesson 12

Lesson 12:
Acids and Bases


First off we made Turmeric Paper. To do this put 1/4 cup alcohol in a bowl and stir in 1/4 tsp of turmeric. Dip coffee filters in the solution until completely covered and yellow. Hang up or place on a cookie sheet to dry.
Once dry, cut them into strips. Now they can be used to test for bases....and acids.
(recipe taken from Janice VanCleave's Chemistry for Every Kid)

Now on to our experiment....

We had a very simple discussion on what acids and bases were. I mentioned that acids have excess hydrogen and bases have excess hydroxide. But mostly we talked about the properties....in terms they know....stomach acid, acid rain, sour, sharp, etc....

We had several solutions to test:
milk, lemon juice, hydrogen peroxide, water, baking soda, borax, saliva, vinegar, bleach water....

One by one we tested them using our turmeric paper....if they produced no change we knew it was not a base...either acid or neutral. If the strip turned red, the solution was basic.

Once we went through all the solutions one time, we retested those solutions that produced no change, but this time we tested them on the strips that were already red. If the strip stayed red....it was most likely neutral. If it turned back to yellow the solution was an acid.

Here's a sample of a basic solution:

Here's a sample of a acidic solution:

Once we ran through our tubes, they went to the kitchen and picked a couple more: apple juice, alcohol and pedialyte.

The results:

acids: lemon juice, peroxide, vinegar, bleach, apple juice and pedialyte
bases: baking soda (with water), borax (with water) and milk
neutral: tap water, alcohol and saliva
_________________

The End
And that concludes our chemistry unit....our 4 weeks are up and we are moving on to Rocks and Minerals....provided I can get it all planned in the next week. We've had a lot of fun with Chemistry though....so we might throw some random experiments in from time to time....

Chemistry Unit- Lesson 11

Lesson 11:

Determining if a chemical change has occurred by observation of generation of heat.

Supplies:
1 tsp yeast, 1/4 cup hydrogen peroxide, stirring stick, thermometer

Record beginning temp of the peroxide (67 degrees)

Mix yeast into the peroxide and stir

The mixture begins to bubble and fizz....another sign that a chemical reaction is taking place. If you keep your hands on the outside of the bowl you can feel it begin to heat up.

Record ending temperature (90 degrees)

They were actually pretty amazed by this one. I keep listing the ways to tell if a chemical reaction has taken place....they've seen the bubbling, they've seen the gas given off.....I guess they didn't really believe that heat could actually be created by just mixing 2 things.

Chemistry Unit- Lesson 10

Lesson 10:

Chemical Changes

Objective: To see a color change as evidence of a chemical change
To see fizzing/bubbling as evidence of a chemical change


Supplies:
3 tubes, labeled #1-3
bleach
vinegar
hydrogen peroxide
3 tubes half full with water
food coloring

Procedure:
Place the bleach, peroxide, and vinegar in each of the tubes labeled #1-#3.
Drop one drop of food coloring in each of the water-filled tubes.

Place one dropper full of solution #1 into one water-filled tube. Observe. Continue for each of the 3 solutions.

The bleach will produce an immediate color change. The vinegar will produce none.

Over the next few minutes the tube with bleach added will become more and more colorless. I added the peroxide on this one. I thought it would produce some sort of change, considering it is used to bleach some things....but no change occurred. Even after adding more than one dropper full.

Experiment 2:

We've done this one before. But it was a hit then, and this time we talked a little more about the why behind it and what was taking place.

Step 1: Fill up a bottle/tube about half way with vinegar
Step 2: Funnel a couple of tablespoons of baking soda into a balloon.

Step 3: carefully stretch the neck of the balloon over the bottle. Be sure not to allow the baking soda to fall into the bottle yet.
Step 4: Lift the balloon to allow the baking soda to fall into the bottle and mix with the vinegar. You may want to hold on to the neck of the bottle/balloon just in case.
Step 5: Watch! The balloon will inflate as the reaction between the vinegar and baking soda produces carbon dioxide.

Chemistry Unit- Lesson 9

Lesson 9:
Physical or Chemical?
6 trays set up as follows:

tray 1: a bowl with an ice cube
tray 2: a tube containing vinegar and one containing baking soda.
tray 3: an apple, plate and a knife
tray 4: a tube containing vinegar and a bowl containing steel wool
tray 5: a plastic back containing a rock and a hammer

tray 6: a candle and a lighter

Their job was to determine whether a chemical change, physical change or both took place.

Phyiscal:
the ice- changes in state of matter
the rock- change in shape
the apple- change in shape

Chemical:

the apple- color change caused by oxidation
the steel wool- rust formation caused by oxidation
the baking soda and vinegar- bubbling, gas formation

the candle- gas formation, odor

We watched the candle (small, birthday cake candle) until it was completely gone. This showed even more than the previous experiment....the wax was almost completely vaporized, where as the previous one had a substantial pile of wax left once it was burned out. While it burned we talked about the parts of the flame. Where it is the hottest, coolest and what is going on in each part. We also talked about open flame safety rules.

I am also fairly certain I could give them a box of baking soda and a bottle of vinegar and they'd be entertained for a very long time.

Chemistry Unit- Lesson 7 and 8

Lesson 7:

Chemical and Physical Changes


We started by defining what a chemical change and a physical change is. Then they came up with some examples of each type. I also told them some of the ways to tell if a chemical change has occurred:

* a precipitate (I used the word solid for them) forms
* fizzing/bubbling
* a color change
*odor, heat or light is given off


Then we moved on to the experiment:

This was mostly observation. In the balance we set up foil, with clay (as a holder) and a candle and balanced it using other objects. We talked about the physical properties of the objects. Then we lit the candle and they talked about what they saw- the size of the candle changing, the wax melting to liquid then hardening back to solid. The smell in the smoke as the wick burned. And other chemical and physical changes the objects were undergoing.

Lesson 8:

Question: Did a physical or chemical change occur?

Hypothesis:
R: physical
C: chemical

Procedure:
Mix 3/4 cup of warm water, 1 cup glue and a few drops of food coloring in a bowl.
In a cup mix 1/2 cup warm water and 2 tsp borax.
While stirring slowly pour the borax solution into the glue solution.

Results:

(a solid forms!)

Conclusions:

A chemical change occured...

And it's a fun change too!

Chemistry Unit- Lesson 5 and 6

Lesson 5: Separation of a mixture

Chromatography

First we reviewed the definition of a mixture and the ways to separate them. Then I mixed 3 colors of water and we discussed how it was a mixture of pigment and water and how we could separate each of the colors back out again.

I gave them a brief description of chromatography and what it meant. Then using 4 different black pens they drew on coffee filters. Then we set dampened cotton balls on the filters and allowed the water to slowly absorb into the filter paper. The above picture is of one of the black inks which separated out into yellow, red and blue....

They started to test all the markers then....they hypothesized that the blue wouldn't separate at all since it was a primary color, but were surprised when purple and light blue came out.

Lesson 6: Solubility

First was vocabulary: solution, solute, solvent and solubility

Then a refresher on the scientific method. This time I wanted them to follow the steps and pay attention to the process....

The Problem:
Which solvent will hold the most solute?
Which solute has the greater solubility?

The Hypothesis:

Cale guessed that the water would dissolve more, Rylan guess the alcohol
Rylan said sugar would have the greater solubility, Cale guessed Epsom Salts, Cohen guessed table salt.

The Procedure:

First we measured out 35 mL of water in to each of 3 tubes. They chose which solute they would dissolve first and scooped 1/2 tsp of that solute into the water. Capped the tube and shook. They repeated this process until the solute would no longer dissolve. Then they repeated the same process, but this time using alcohol as the solvent.

The Results:

	Water	Alcohol
Salt	4 scoops	2 scoops
Sugar	18 scoops	6 scoops
Epsom salt	18 scoops	>1 scoop

the sugar dissolved just a little bit more than the Epsom Salts in the water.

Conclusions:

Water can hold more solutes, and we discussed a little about water being the universal solvent. Sugar had a greater solubility in both solvents.

It was nice to see them bringing in information from the past lessons...Rylan was talking about molecule size and noticing that the volume of his tube (with 18 scoops of sugar) was about to overflow, but Cale's (with 18 scoops of Epsom salts) still had about 1.5 inches to the top of the tube. Cale had a hard time with that- since the visual size of the E. salts are much bigger than the sugar crystals.

Chemistry Unit- Day 4

Mixtures and Separation


First we talked about what a mixture was and they came up with some examples. Then I had them mix the first set of tubes in front of them- chick peas and sugar. And I asked them what the best way to separate them would be. Both Rylan and Cale said to add water at first, but I told them I wanted the sugar back, not have it washed away.

So we talked about the first way to separate a mixture: filtration. Cohen and Lakin poured out the sugar/chick pea mixtures into a colander to separate.

Then I gave them the second set of tubes- water and soil. Which Cohen and Lakin shook up real good while I had Rylan and Cale think of how to get the soil back out. They both agreed that the colander wouldn't work, but that a smaller filter would. So Rylan poured his out into a coffee filter to separate and while it drained we talked about an other option.


While we had been talking the second tube had been sitting there untouched. So when I asked them to look at it they saw the second way of separation: settling. We set the tube up on the shelf to allow it to settle completely.

Then they each got a one tube containing water and one containing sugar. I had them combine them and shake until the sugar was dissolved. Then I asked for them to give me the sugar back. I had them start by using the previous 2 methods. Cale poured his through a coffee filter, Rylan set his up to settle. And after some discussion we set Cohen's on the windowsill to evaporate the water and leave the sugar.

Since everyone agreed that evaporation would leave the sugar behind, I asked them for the water back too. If it evaporated it would be gone....

So we went into the kitchen to try distillation. We only caught a little bit of the steam to condense back into water then we just let the steam go and watched the sugar crystals form back in the bottom of the pot.

We talked a little bit about why you would want to capture the gas as it evaporated. How some gases are harmful to the earth or to people. Then they ate what they could scrape out...

Chemistry Unit- Day 3

Chemistry Unit- Day 3
How Matter Takes Up Space

background information: First we discussed what atoms are and how they come together to form molecules. We compared atoms to letters and molecules to words. We briefly looked at the Periodic Table of Elements.

Activity 1: Marshmallow molecules

Today we had a couple friends over to join in on our chemistry experiments. I gave each kid a sheet with a color key for the marshmallows- white were oxygen, pink was nitrogen, etc... We used Hydrogen, oxygen ,nitrogen, sodium and carbon. The sheet also listed a few common molecules that they would be familiar with.

Then they started building- starting with molecular oxygen. Then to carbon dioxide, water, vinegar, ammonia...

Baking soda is pictured above. We talked about symmetry, but since these guys are all under the age of 9, I didn't go into detail about bonds or any of that.

Then they built their own molecule however they wanted. While they did that we talked about how all the ones they made were different sizes and take up different amounts of space.

Experiments 2 and 3

The next 2 experiments dealt with how mixing different types of matter/molecules effect the volume. We started off adding 25 mL of water and 25 mL of water. We measured out the amounts and they each took a guess as to what the volume would be when they combined the 2 tubes....most guessed 50 mL. Which was correct.

The next part we combined unlike matter/molecules. We measured 25mL of water in one tube and 25 mL of alcohol in a second tube. Then they recorded their guess as to what the final volume would be. Most thought it would still be 50mL, Rylan thought it would be less.

When they combined them the result was just under 50 mL....and we talked about how the alcohol molecules were a different size than the water so they fit together in different ways.

Experiment 4:
This was the second experiment dealing with mixing unlike matter. The kids filled their tube up about half way with salt. Then added water to a couple centimeters above the salt and marked the level on the outside of the tube. Then they took their guess- after shaking would the level of the mixture be above, below or at the line . 2 said at, one said above and one said below. Then they shook

And recorded the result- under the line. And we talked about how shaking evenly distributed with molecules of salt and water, making them take up less space.

Experiment 5: Visualization

This final exercise was to see how the different sized molecules share a set volume. We started off with large "molecules" which were marbles. They took a guess as to how many scoops of marbles it would take to fill the tube. Then they filled them up...and recorded the actual.

Then I asked them if the tube was really full? There was a lot of empty space in between the large molecules. And I asked them to guess how many scoops of "smaller" molecules it would take to fill up the tube the rest of the way. So they started to add scoops of popcorn kernels to the tubes until they were full.

Finally I asked them if it was full again, and then to guess how many scoops of "tiny" molecules it would take to fill the tube. Some said zero some said 20....then they added sand...tapping the tube after each scoop to fill in all the gaps.

Once that was done I asked them what would happen if they had started with the tiny sand. Would they still be able to fit 10-12 marbles in their tube?

They gave it a try- here are Cale's. On the left was 12 scoops of marbles, 6 scoops of popcorn and 8 scoops of sand. On the right he got the 8 scoops of sand and 6 scoops of popcorn but only 1 marble could fit. Since the sand "molecules" could fit so close together the larger marble "molecules" couldn't fit in between them.

Chemistry Unit- Day 1 and 2

Day 1:

This was a quick lesson since we had our co-op classes in the morning and had a vet appointment in the afternoon. But we started with discussing matter. What it was and the 3 major forms it takes. We gathered some items and I had them sort them into solids or liquid, or both.... venn diagram-style using yarn circles. Once they were sorted we added the 3rd circle for gas. I had them look over each item to see if any of them had gas in them. They did immediately see the air bubble in a couple of the liquids and the air inside the dogs squeaky toy.

We also talked about the properties of solids, liquids and gases. And since I put up a posted of the periodic table of elements we had a short talk about that, atoms and molecules.


Day 2:

We started off reviewing the definition of matter again. Then we tested to see if certain object did indeed take up space and have mass. So using our scale and balance they tested for awhile. Then I asked them about gases. If it weighed anything. Cale said no. Rylan remembered we had done this particular experiment before and said yes. So we took 2 balloons on either side of the balance. They were equal. Then Rylan blew up one balloon. And they guess if one side would be heavier now. Then it was easy to see that the gas inside the balloon 1. took up space since it was visually larger than the deflated one and 2. it had mass since it was heavier blown up

Next we talked about the behavior of the molecules in solids, liquids and gases. We started off with a demonstration using marbles in a box. To demonstrate solids, the box was filled completely so that they could barely move. This shows that the molecules move slow and are packed closer together. Which is why solids are hard and don't form to the shape of the container they are in. For liquids we removed some marbles so that they could roll around a bit and move faster. We removed even more to show that the gas molecules can move very fast.

Once that was done we talked about the 3 forms of water and how the molecules would be moving in there. How the colder water gets, the closer to being ice (solid) the slower the molecules will be moving. And the hotter water gets, the closer to steam (gas) the faster the molecules will be moving. We filled 1 tube with cold water and 1 with hot. They gave their guess as to which tube would mix the color quicker- the cold or hot. (Pictured above) The cold wasn't too much slower, but it took longer to get a uniform color than the warm water.

From here they wanted to try really cold and boiling water. So we filled 1 tube and stuck it in an ice bucket and boiled some water in the microwave for the second. This time the results were much more dramatic. The boiling water mixed almost instantly. The colder water started off pretty well but stalled once the dye hit the bottom where the water was even colder.

Rylan wanted to go even further, so we placed the dye on ice...to see how quick it would mix

At first they thought it was going quicker than expected

Only to realize the ice wasn't mixing, the dye was just mixing with the water as it melted....

and they went back to their original guess- that it wouldn't mix completely until the ice melted.