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MOVING MOLECULES, PHYSICAL PROPERTIES, CHANGES
Part 2 - KID'S CHEMISTRY

Part 2 - KID'S CHEMISTRY


Pat Kellogg Roller, Children's Science Specialist/Teacher/Retired
Pat Kellogg Roller, Children's Science Specialist/Teacher/Retired


PART 2 - HAVING FUN WITH  "KID'S CHEMISTRY IN THE KITCHEN"
                 "High interest hands-on kids chemistry experiments."

"Beginning chemistry prepares students for high school chemistry" without fear. Here we begin in grade 4. "Experiments develop creative problem solving skills in our kids."


MOVING MOLECULES,  PHYSICAL PROPERTIES AND CHANGES IN: Solids, Liquids, and Gases

"EASY INTERESTING EXCITING KID'S CHEMISTRY EXPERIMENTS" AND ACTIVITIES 

EXPERIMENT 1 - ICE- WATER - WATER VAPOR

"EVAPORATION - CONDENSATION -  WATER CYCLE"

"MOVING MOLECULES" - DIFFUSION

DENSITY EXPERIMENT - MOLECULES MOVE!

TEMPERATURE EXPERIMENT - MOLECULES MOVE!


BACKGROUND:    "Knowing begets caring."
Knowing Begets Caring

KNOWING BEGETS CARING

MOLECULES form when atoms of elements come together. Chemists study molecules of Earth Stuff (matter).

Atoms of elements may share, gain, or lose an electron. If an atom loses an electron, it becomes a positive ion because it has more protons than electrons. It has a positive electrical charge.

If an atom gains an electron, it becomes a negative ion because it has more electrons than protons. It has a negative electrical charge.
Since opposites attract, these two atoms may join to become a molecule.

Sometimes two atoms of the same element will join. Sometimes an atom of a different element will join to another element to become a molecule.

Sometimes two atoms of two elements will share an electron.

It is this gaining, sharing, or losing an electron, which helps to create many new substances, which may be mixtures or compounds.
 
                                                                     "STATES OF MATTER"

MOLECULES of matter are always moving. Matter may a solid, a liquid, or a gas. Matter can change its shape from one state to another by adding heat or cold to it.

SOLIDS – Molecules are very close together and move very slowly. They vibrate.

LIQUIDS – Molecules move faster and take the shape of their container.

GASES – Molecules move very, very fast. They quickly fill the container and may move outside the container.
                          




PHYSICAL CHANGES IN MATTER

All that exists on earth besides matter is energy, and energy makes things move!

Physical changes are concerned with energy and states of matter. A physical change does not produce a new substance.

Changes in state (melting, freezing, evaporation, condensation) are physical changes.

Examples of physical changes include crushing a can, melting an ice cube, breaking a bottle, wadding up or cutting up paper.
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 EXPERIMENTS - MOVING MOLECULES, PHYSICAL PROPERTIES, PHYSICAL CHANGES

Another step in learning  "how our planet works."

aNOTHER STEP IN LEARNING HOW OUR PLANET WORKS

HOW OUR PLANET WORKS.


Goal:  To understand that a solid may be changed to a liquid, or a liquid to a gas by adding heat.

Skills: Observing, describing, predicting, experimenting, supporting inferences with observations, identifying  and controlling variables, measuring, and generalizing.

BACKGROUND INFORMATION: Molecules

Matter may be a solid, a liquid, or a gas. Matter may be changed from one state to another by adding heat or cold. Experiment 1 helps students  understand these three states of matter in water and how the states may change. 

These changes are called physical changes. They do not produce a new substance. Physical changes may be reversed.  Examples of physical changes include: melting, freezing, evaporation, condensation, crushing a can, wadding up or cutting paper, breaking a glass bottle.

Physical Properties are used to describe changes in matter. They involve the five senses such as describing matter by its: color, size, state, texture, hard or soft, rough or smooth, temperature etc... 

                                                                
KIDS LOVE TO DO "HANDS-ON' CHEMISTRY EXPERIMENTS!

                                                           END BACKGROUND INFORMATION
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EXPERIMENT 1 - ICE - WATER - WATER VAPOR

ORGANIZATION: Students work in groups of four or five  students using the "COOPERATIVE LEARNING GROUPS IN THE LAB" to organize themselves. A copy of this can be found in "PART 1 - KID'S CHEMISTRY

MATERIALS: For each pair of students, 1 ziploc baggie, 1 ice cube, 2 paper towels, ml measuring container (baby food jars with marks are O.K.),

MATERIALS FOR TEACHER DEMONSTRATION: ice cubes, water, ml measuring containers, paper towels, hot plate, medium size pan to heat water in, tall clear glasse or pint jar, food coloring, a plate to hold above the pan of boiling water, a watch

PREPARATION TIME: 5-8 minutes

PROCEDURE AND QUESTIONING

When each pair of students has an ice cube in a baggie, and a ml measuring container, ask them to describe the physical properties of the ice cube. (See physical properaties in information above.)


Tell the students, "We're going to see who can change their solid ice to liquid water fastest. You will have two minutes to discuss with your partner how you will do it, and five minutes to conduct the experiment. 

RULES: Must stay in your seat, and you can not make holes in the baggie.

Start experiment. Stop it in five minutes. Ask students to open their bags and pour the liquid water into the measuring cup and measure how much water is in the container. . 

Ask the students what caused the ice to melt.(heat)  Let them share different methods they used to melt their ice cube. Determine which students melted the most ice and ask them to share how they did it.

In melting the ice cube students had to apply heat in some way. Ask them to think of other solids you can melt by adding heat. Iice-cream, popsickles, chocolate, candle wax, etc...)

Ask students what would happen if we boiled the water they collected? Collect the water and put it in the pan on the hot plate to boil.

When it begins to boil hold a plate several inches above the pan so the water vapor collects on the plate as liquid water.

Ask the students how the liquid water got on the plate? Hopefully someone will stay the water changed to water vapor (a gas), then when it hit the cold plate it changed back to liquid water.

SUMMARIZE HOW THE ICE CUBE CHANGED TO WATER BY ADDING HEAT; AND THE WATER CHANGED TO WATER VAPOR (GAS) BY ADDING MORE HEAT.

                                                                   END EXP. 1
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EXPERIMENT 2: EVAPORATION, CONDENSATION, AND THE WATER CYCLE

Fill the clear glass half full of water and add ice cubes until the glass is full. Add a few drops of food coloring to this water.

Ask the students to predict what will happen. (Some will say the ice will melt.)

Wait until liquid water begins to form on the outside of the glass.

Ask the students where the water on the outside of the glass came from? (Some may say from the water inside the glass.)

Ask the students what color the water is on the outside of the glass? (clear)

Ask the students what color the water is on the inside of the glass?(colored)

Hopefully, someone will say the water on the outside of the glass came from the water vapor (gas) in the room air. Someone else may add that the water vapor changed back to liquid water when it touched the cold glass.

Tell the students that when the water in the pan boiled and changed to a gas that is called "evaporation."

Then when the water vapor in the air touched the cold glass it changed back to liquid water on the outside of the glass. That is called "condensation."

SUMMARIZE: Water may be in the state of a solid, a liquid, or a gas. By adding heat or cold we can change it from one state to another.

Ask them if the water becomes a new and different substance when it changes state?  

Students say, No, the water can shape its shape or state but it is still water.

Tell the students the water went through PHYSICAL CHANGES ONLY. The changes can be reversed.

A PHYSICAL CHANGE does not change the atoms in the molecules and it can be undone.

Ask students to name some examples of physical changes in matter. (melting, freezing, evaporation, condensation, break a glass bottle, cut a piece of paper, was up a piece of paper)

                                                                       END EXPERIMENT 2
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ACTIVITY: STATES OF MATTER, WATER CYCLE, ENERGY CONSERVATION

MAKING CONNECTIONS: More about our "amazing Planet Earth"


                                                     CARING FOR OUR AMAZING PLANET EARTH

                                                     Caring for our amazing Planet Earth
Students, let's talk about rain

What is rain? (liquid water)

Where does rain come from? ( the sky?)

How did it get there so it can fall down?

Ask students to remember the experiments they have done. Review them together.

Then ask them if they can see a connection between the experiments and how rain works.

                                                      "EARTH AWARENESS - EARTH CARE"

BACKGROUND:
 Most of the water on earth is salty and we can't drink it. Some of the fresh water is tied up in glaciers. Only a small amount of earth's water can be used as fresh water. This same water is used over and over. You may drink water today that was used by an Eskimo to take a bath last year. That small amount of water is all there is. We cannot go outside our planet and get more.

How does the earth use the same fresh water over and over? Can you use the experiments with ice-water-water vapor (gas) to explain?

Allow time for the student's ideas. After a while help them pull it together and write it up like this:

The sun heats up the water in our ponds, lakes, streams, and rivers, and some of it changes to water vapor (gas) and rises into the atmosphere. This is called (evaporation.)

Does salty ocean water evaporate? (Yes, but it leaves the salt behind.)

When the water vapor in the air comes in contact with a lot of cold air, the gas changes back into liquid water and collects in clouds. This is called condensation. If there is enough water in the air, it will fall through the air to the earth as rain, sleet, snow, or hail.

What do we call this process? (The Water Cycle)

Have students draw a model of the Water Cycle and label the parts explaining how it works.

THE TEACHER SHOULD TURN THE QUESTIONING TO THE AIR WATER FALLS THROUGH, AND WHAT THAT IMPLIES.

What happens to rain when it falls through dirty (polluted) air? (It gets dirty too.)

What causes air to get dirty (polluted?)  (dust, soot, gases formed when fossil fuels are burned as gasoline or to generate electricity. The fossil fuels are: coal, oil, and natural gas.

What are scientists and engineers doing to help clean our air? (They are developing alternative sources of energy which do not pollute the environment such as solar energy, wind energy, biomass energy from plants and animal waste, fuel cells, etc... These sources do not pollute the air when they are used to make electricity.

What can we do to help clean the air? GENERATE ANSWERS FROM THE STUDENTS.

Some Ideas: use less gasoline, walk, carpool, or ride our bikes. 

We can save electricity, which is mostly made from coal, oil, or natural gas, by closing outside doors and refrigerator doors when not in use, use less water by taking short showers and turning off the water taps when not in use.

We can help clean and cool the air by planting trees, by growing backyard gardens, and by recycling paper, plastic,and metal cans. We can avoid littering.

                                                                          END ACTIVITY
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                                                                       DID IT WORK?

Quizzes are important. I like to make up review questions and let the kids work in groups to review and prepare for the quiz. I like to give short quizzes. For kids who do not read well, I usually put the test questions on a tape with a paper copy of the test and they can write the answers on the test sheet or give oral answers with the tape recorder. I like for everyone to enjoy science and to be successful. The extra effort is worth it.
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                                                             "MOVING MOLECULES (Diffusion)"

PROBLEM: How does density and temperature affect the diffusion of food coloring in liquids?

MATERIALS: ice water, warm water, rubbing alcohol, skim milk, 8 tall clear glasses (or pint or quart jars), one color of food coloring, stop watch, thermometers, lab sheets (a chart would be nice).

Note to the teacher:  With older students, you could do density and temperature at the same time, but I prefer to keep the two separate. It is easier for the students.

(Note for the teacher only.) Put out only one color of food coloring for all experiments. (Alcohol is least dense, water next, and skim milk most dense. Food coloring moves fastest in alcohol and in very warm water; and slowest in ice water and in skim milk. When the students observe this you can ask the following questions.

Ask, “Is the food coloring mixing with the room temperature skim milk? _______________ Is the food coloring moving very, very slowly?”_______.

Ask “Can you think of a way to get the food coloring to mix with the skim milk?”   RULE: You can’t shake it or stir it.  Visit with your group members and see if you can come up with an idea to make the food coloring mix with the skim milk fasterLook at the results of the water experiment for help?

(Note for the teacher (continued) It is good to allow one group of 4-5 students to demonstrate one part of each experiment for the class to observe. I suggest the teacher control the stopwatch and let students do the rest. Refer to Cooperative Learning Groups Lab. ( See Part 1 - Kid's Chemistry, near the end of that section.

Be sure students put the same amount of liquid and drops of food coloring in each container in every experiment. In this way, you control these two variables. Talk to your students about the importance of controlling variables in order to know what caused the results.

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STEP 1: DENSITY EXPERIMENT  “ MOLECULES MOVE”

Ask students to predict which liquid, alcohol, water, or skim milk will be most dense (thicker) at room temperature.
To test this, set up three clear glasses or jars. Put the same amount of one of the  liquids in each container.

Take the temperature of each liquid to be sure they are all at room temperature. Record temperatures.

Test one liquid at a time and record results.

Drop food coloring into alcohol, immediately start stopwatch. Record time it took the food coloring to color all the alcohol.

Using the same number of drops of food coloring, repeat this experiment with the room temperature  water, and skim milk . Record time for the food coloring to color each of the liquids.

If diffusion of food coloring in the skim milk is proceeding very slowly, ask students how they might speed up the diffusion process.Don't allow them to stir, or shake the milk.

Ask students what they learned about diffusion and the density of the liquids.  After discussion, summarize the results.

FACT: The more dense (thicker the liquid), the more slowly the food coloring will diffuse into the liquid. Density does matter in moving molecules.

Which liquid was most dense? _________ List the liquids in order of least dense to most dense. _____________________________________________

BIG IDEA: Heat will increase and cold will decrease the speed of molecular movement in water.
 
                                                             END DENSITY EXPERIMENT

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STEP 2:  TEMPERATURE EXPERIMENT: “MOLECULES MOVE” Test one liquid at a time and record the results.

PROBLEM – In which liquid will the food coloring move fastest – slowest?

PREDICTION: (Students write down the four liquids in the order of fastest to slowest.)

USE EXACTLY THE SAME AMOUNT OF LIQUIDS AND THE SAME AMOUNT OF FOOD COLORING IN THE SECOND EXPERIMENT AS IN THE FIRST. (Control these variables).)

RECORD THE RESULTS OF EACH PART OF THE EXPERIMENT AS YOU DO IT.
Fill a glass with very warm water, take the temperature of it, then drop in food coloring and use stopwatch to time the diffusion of the food coloring and water.(Teacher controls the stopwatch.) Record temperature and time.

 Repeat the experiment with room temperature water. Repeat the experiment with ice water (very, very cold).

Compare the results of the room temperature water, the very warm water, and the ice water.

What was the effect of temperature in the diffusion of water, warm water, and ice water?  Discuss results and summarize.

(Fact: The warmer the water, the faster the diffusion of food coloring in it.)

Repeat the experiment with alcohol and with skim milk.Record results.

Go back to the Density Experiment and see how long it took the diffusion to happen in the alcohol and skim milk.

Did the temperature of the alcohol and skim milk match the diffusion rate in the Density Experiment?  

Why do you think it took longer for the food coloring to mix with the skim milk when both were the same temperature to start with?

__________________________________________________________________________________________________________


Discuss results. Did temperature have an effect on the rate of diffision?  ______  In which liquid? ______________

How did the students change the skim milk to get the coloring to mix with the milk faster?  What did they learn about diffusion in liquids?

WRAP-UP AND PRACTICAL APPLICATION: With student assistance, write up what they learned about the rate of moving molecules in liquids; tested for the effects of density and temperature on the rate of diffusion of food coloring in the liquids.

(Note the temperature caused a change in the rate of diffusion, only in the room temperature water, the very warm water, and the very ice water.) The alcohol and skim milk were at room temperature in the beginning of the experiment.

Hopefully, students will realize that both density and temperature of the liquids had an effect on how fast the molecules moved to spread the food coloring in the liquid.

Ask students, how could we use what we learned about density and temperature of liquids today?
(Use less sugar by sweetening my tea, lemonade, or Kool-Aid, while it is warm. Warm up the pancake syrup and it spreads better and faster on the pancakes; keep my favorite cold drinks in the refrigerator so it takes less ice to cool them down, etc...) 

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