LESSON 7: WHEN YOU LOSE WEIGHT, WHERE DOES IT GO? (WHAT IS MATTER?) SUMMARY Students will learn about forms of matter and the conservation of mass through building their own “lava lamps.” Students will understand that when matter is transformed from one form to another, it maintains its mass, even if that mass changes from visible to invisible. ESTIMATED TIME 30­50 minutes LEARNING OBJECTIVES Learners will learn... Learners will be able to... 1. The three most common states of matter. 1. Identify the states of matter. 2. The concept of conservation of mass. 2. Categorize anything into solid, liquid or gas. Building on Lesson 2, students will learn 3. Identify, in any transformation of matter, that every transformation of matter only which initial form of matter has been affects the ​
spacing between atoms​
and converted into which second form of matter molecules that make up matter; atoms (liquid­­>gas, gas­­>liquid, etc.). and molecules do not disappear. 4. Recognize the conditions that are 3. Where important transformations of matter associated with specific transformations, occur: plants and animals (including such as cooling (e.g., gas­­>liquid) or humans). heating (e.g., liquid­­>gas) or metabolism (e.g., milkshake [“sugar” in liquid form]­­>gases or bagel [“sugar” in solid form]­­>gases). Reference: http://www.primaryscience.ie/media/pdfs/col/seai_chemical_energy.pdf NEXT GENERATION SCIENCE STANDARDS Structure and Properties of Matter ​
(5th grade) 5­PS1­1. Develop a model to describe that matter is made of particles too small to be seen. 5­PS1­2. Measure and graph quantities to provide evidence that regardless of the type of change that occurs when heating, cooling, or mixing substances, the total weight of matter is conserved. Disciplinary Core Ideas PS1.A: Structure and Properties of Matter ­
Matter of any type can be subdivided into particles that are too small to see, but even then the matter still exists and can be detected by other means. A model showing that gases are made from matter particles that are too small to see and are moving freely around in space ­
can explain many observations, including the inflation and shape of a balloon and the effects of air on larger particles or objects. (5­PS1­1) The amount (weight) of matter is conserved when it changes form, even in transitions in which it seems to vanish. (5­PS1­2) PS1.B: Chemical Reactions ­
No matter what reaction or change in properties occurs, the total weight of the substances does not change. (5­PS1­2) Science and Engineering Practices ­
Use models to describe phenomena. (5­PS3­1) ­
Analyze and interpret data to make sense of phenomena using logical reasoning. (3­LS3­1), (4­ESS2­2) ­
Use evidence (e.g., observations, patterns) to support an explanation. ​
(3‐LS3‐2) ­
Use evidence (e.g., measurements, observations, patterns) to construct an explanation. ​
(3‐LS4‐2), (4‐PS3‐1) ­
Support an argument with evidence, data, or a model.​
(5‐LS1‐1) Crosscutting Concepts ­
Matter is transported into, out of, and within systems. (5­LS1­1) BACKGROUND INFORMATION FOR TEACHERS Read the following information as a refresher for yourself and try to infuse it into the lesson. Matter is everything that takes up space, and has mass.The three most common forms of matter are: solids, liquids, and gases. A solid is anything that has its own shape. A liquid flows and will take the shape of the container it is in. A gas, though not visible, will spread out and fill all available space. One way to visualize this is that the molecules that make up matter­­think of a gallon of water molecules!­­are never created, and are never destroyed. No matter if those water molecules are frozen, melted into liquids, or evaporated into gas. So matter can not be created or destroyed, only rearranged. Matter can change from one form to another. In perfect conditions, water can transform from liquid water to ice to vapor and no mass will disappear. This is called the “conservation of mass.” Mass is the amount of matter and is commonly measured by how much something weighs. However, weight can change and mass cannot. For example an object on Earth may weigh more or less on another planet due to changes in gravity but its mass will stay the same. Matter also has different densities. The density of a substance is the relationship between the mass of the substance and how much space it takes up (volume). The mass of atoms, their size, and how they are arranged determine the density of a substance. ​
Solids are generally more dense than liquids: they have more atoms packed into the same space. The atoms are tightly packed together and stay in shape all by themselves, though they do move about on the spot. Liquids are usually less dense than solids but more dense than gases. Their atoms can move around much more, so they need a container to keep them in place. Gases are even less dense than liquids. Their atoms go where they please, so they need a completely sealed container to keep them in place. A cubic yard (a box 1 yard long by 1 yard high by 1 yard wide) of ice would weigh about 1500 pounds. A cubic yard of liquid water would weigh about 1680 pounds. A cubic yard of air (with only 10% water vapor) would weigh about 2 pounds. MATERIALS AND PREPARATION ● computer ● Google Docs KWL Chart (shared below) ● “What is Matter?” Questionnaire (​
http://bit.ly/UTRACmatter​
) ­ link below too ● empty soda bottles (multiple [minimum 1] per student) ● fizzing (alka seltzer) tablets (1 per student) ● non­fizzing (vitamin C) tablets (1 per student) ● water to partially fill containers (ratio in reference document and instructions below) ● vegetable oil to partially fill containers (ratio in reference document and instructions below) INTRODUCTION: 10­15 minutes 1. Tell the students that today’s mystery is “When you lose weight, where does it go?” Quickly ask them what they think the answer is, then tell them they will find out at the end of the lesson. 2. Quickly review the following concepts that were covered in lesson 2. a. Matter is everything that takes up space, and has mass. b. The three most common forms of matter are: solids, liquids, and gases. 1.
A solid is anything that has its own shape. 2.
A liquid flows and will take the shape of the container it is in. 3.
A gas, though not visible, will spread out and fill all available space. c. Names and common examples of three states of matter: solid (for example, wood, rocks), liquid (for example, water), gas (for example, air, steam). d. Matter can change from one form to another. An example would be, ice, which is a solid; melts and becomes water, which is a liquid; and when boiled (212 degrees Fahrenheit or 100 degrees Celsius) becomes steam, a gas. In fact, because of Bozeman’s elevation, water boils at 203 degrees Fahrenheit. e. Ask the students if plants, animals and/or people can change the state of matter? Explain that all three can. Plants take water and convert it into oxygen. You and your pets can eat solid and liquid food and convert them to gas­­including the stinky variety. Have you ever wondered what happens when people lose weight? Where does the mass go? It turns out you breathe most of it out as carbon dioxide and water vapor, so you convert a large part of the liquid and solids you eat to gas. f. Ask the students if temperature plays a role in matter changing states? Guide them to recognize the conditions that are associated with specific transformations, such as cooling (e.g., gas­­>liquid) or heating (e.g., liquid­­>gas) or metabolism (e.g., milkshake [“sugar” in liquid form]­­>gases or bagel [“sugar” in solid form]­­>gases). g. The principal forms of matter­­solid, liquid, gas­­reflect an upward RAMP of spacings between atoms, from closer to more distant, as in this figure. h. Have the students count the number of red dots in the diagrams below. The red dots represent (red) molecules of water, each of which can be represented chemically through the combination of two atoms of hydrogen (symbol H) and one atom of oxygen (O). Fill in the table. Solid Liquid Gas i. Ask the students how it is possible that the numbers they listed are NOT be the same number? Remind students that matter can not disappear. j. Answer: The key is the caption, that was never shared with students: these are representations of forms of matter “in the same space”­­which means volume. That space could be a gallon of milk! From​
​
http://www.explainthatstuff.com/states­of­matter.html​
: i.
Left: Solids are more dense than liquids: they have more atoms packed ​
into the same space​
. The atoms are tightly packed together and stay in shape all by themselves, though they do move about on the spot. Middle: Liquids are usually less dense than solids but more dense than gases. Their atoms can move around much more, so they need a container to keep them in place (but an open container is usually okay for short periods of time). Please note that this diagram is a deliberate exaggeration: the atoms in liquids can be almost as close together as they are in solids. Right: Gases are even less dense than liquids. Their atoms go where they please, so they need a completely sealed container to keep them in place. Now introduce this new key concept for this lesson. Matter can not be created or destroyed, only rearranged. For example #1, when ice melts (converts from a solid to a liquid form), the mass of water is unchanged if there is no evaporation. For example #2, when water evaporates (converts from a liquid to a gas form), it turns into water vapor, which is invisible, but the mass is unchanged. For example #3, when water condenses (converts from gas to liquid form, as occurs during cloud formation or when you breathe onto a mirror), the mass is unchanged. (NOTE: These are examples of transformations in ideal conditions.) In none of these cases does mass disappear. This is called the “conservation of mass.” This is a very important principle for students to retain/master/teach for UTRAC. An extension activity is tacked on below to represent the same number of red dots in three different spaces. TEACH: 20­30 minutes 1. The students will be constructing a lava lamp as a demonstration/visualization of the conservation of matter. Follow the directions @ http://www.primaryscience.ie/media/pdfs/col/seai_chemical_energy.pdf​
. They are simplified here. 2. Have students measure the volume of the plastic bottle (if it is not written on it). 3. Have students estimate​
​
a quarter​
of the bottle, and add this amount of ​
water​
. 4. Then continue to fill the bottle with ​
vegetable oil ​
until it is ​
two­thirds​
full. 5. (PROMPT: What happens? Do the oil and water mix? Why or why not?) 6. Wait​
until the oil and water have separated. DO NOT shake the bottles. Point out to the students that the oil floats on the water because it less dense. 7. (PROMPT: Do students think food coloring will color the oil or water or both?) 8. Have students add about ​
10 drops of food coloring​
to the bottle. 9. (PROMPT: What happens to the food coloring?) (The food coloring does not dissolve in the oil, but it does dissolve in the water and colors it). 10. Have students ​
add​
an ​
Alka­Seltzer​
tablet into 3 or 4 pieces and drop one of them into the bottle with water & oil & food coloring. 11. (PROMPT: ​
What can students observe?​
​
Be very careful here​
, as there are a lot of moving parts and it could be quite exciting. You want to channel the student’s excitement back to basics. If the Alka Seltzer tablet disappears/dissolves, does it cease to exist, as in POOF? No. It converts from solid to liquid components as described in Lesson 2. Students should pretend they are scientists. Forms of matter. Expressions of energy.) 12. (Modified from the Primary Science PDF listed earlier.) Where does the energy come from? Answer: Chemical energy associated with the bonds between the different atoms within the Alka­Seltzer is released because of a chemical reaction between those atoms and molecules with the water. That reaction produces carbon dioxide gas, which because it is less dense than the liquid, floats to the top of the lava lamp. For a more detailed explanation of what is happening in the lava lamp see the extensions. 13. Leave the bottle for 5 to 10 minutes or so, observing it from time to time. What do you see? Now add another bit of Alka­Seltzer tablet. What happens? Can you explain? (The same process repeats, i.e. The ‘lava’ erupts again). WRAP­UP: 5­10 minutes 1. Students should complete the second half of the questionnaire a. http://bit.ly/UTRACmatter 2. Revisit concepts behind transformations of matter as related to the lava lamp. Which things confused students? On which items would everyone agree? 3. Revisit the idea that forms of matter are constantly being transformed. Prompt students to provide examples of the transformation of matter OUTSIDE school. For example, when snow “disappears”, where does it really go? What forms of matter does it change into? What source of energy causes the reaction for snow to disappear (the Sun). 4. Ask students to recall their answers to today’s mystery, “When you lose weight, where does it go?” Have their answers changed? 5. Explain that when weight or mass is “lost,” those molecules are not destroyed. They simply are converted to gaseous forms of the very same molecules that cannot be measured from an open container. So the loss of weight or mass is not really a loss, especially if you know where to look­­in the air. When a family member decides they want to lose weight by going on a diet, most of that weight will disappear into the air as molecules of food or skin or fat are converted into gas molecules. The scale they are using to track their weight loss might read a smaller number, hopefully, but that just means that some mass was converted from solid or liquid mass into gaseous mass. Just like the Alka Seltzer mass converted from solid mass into gaseous mass in your Lava Lamp. EXTENSION ACTIVITIES Understanding Transformations of Matter Here is a diagram for processes of transformations of matter that does not include metabolism, which is the conversion by animals (including humans) of forms of matter. Source:​
http://www.explainthatstuff.com/states­of­matter.html Ask students questions to have them help create this diagram. Start by asking them the three most common states of matter, then write them in a triangle as in the diagram. Then ask the students to try and fill in the words on the arrows that describe the transformation of matter. More Information about the Transformation of Alka Seltzer 1. What is it about alka seltzer that enables it to convert from a solid to a gas? Why doesn’t the same weight of mass (e.g., a button or a paperclip) placed in the same volume of water lead to the same transformation? Why doesn’t the same weight of table salt yield fizz? The answer lies in the bonds between the components of an alka seltzer tablet and the bonds between other examples of solids. Fundamentally, alka seltzer is a combination of​
a sa​
lt and​
an aci​
d and, it turns out, aspirin. The only two ingredients for the magic show that matter are the salt and the acid. A great definition of a salt is just something made of elements that when placed in water dissolve into their constituent positively and negatively charged ions. Table salt (sodium chloride) is a familiar example. Its formula is NaCl. As a solid, those sodium atoms are bonded to chlorine atoms; once in water however, those bonds are broken, and the salt dissociates into a positively charged ion (also known as a cation), Na +​
­1​
1, and a negatively charged ion (also known as an anion), Cl ​
. +1
So the salt in alka seltzer is sodium bicarbonate (NaHCO​
), which means that when dissolved it creates Na​
3​
­1​
cations and (HCO​
)​
anions. Why does it fizz when regular old table salt does not fizz? 3​
That is where the second ingredient ­­the acid­­comes in. The acid actually attacks the bicarbonate anion and converts it from bicarbonate into water (H​
O) and 2​
carbon dioxide (CO​
) gas. The water mixes with the original water, increasing its original mass ever so 2​
slightly. Though some of the carbon dioxide will mix back with the water most of the carbon dioxide remains a gas, bubbling into the space above the liquid. 2. Where else could acid come from, besides the original tablet? Here is a zoomed in part of the box of Alka Seltzer and it contains a clue: the word “​
antacid​
,” which means anti­acid or acid­fighting. Hint #1: Stomach acid can have a pH of 2.7. Sometime people develop too much stomach acid. The bicarbonate salt acts as an antacid, absorbing acid, and using it to liberate carbon dioxide. 3. If you are feeling adventurous, and have permission of the afterschool care provider, try overloading a bag of water with many (how many? have your kids figure out the exact number) alka seltzer tablets­­once the ziplock is sealed, the pressure of the gas produced should cause an excellent explosion. Be prepared for a mess. “Kids, try this at home.”