Due Tuesday 12/12

1. Olivia observes that when milk and chocolate are mixed together that the milk changes color. She believes that in order to create chocolate milk a chemical reaction has occurred. Is she right or wrong? Explain.
2. Faith likes to play with glow sticks. She loves that when she bends a new glow stick it suddenly begins to glow. What type of reaction is occurring in the glow stick, chemical or physical? Provide evidence for your answer.
3. On the 4th of July, Bartlett holds a fireworks display for the town. Micah attends each year with his family. Micah explains that fireworks are an example of a chemical reaction. What evidence can Micah use to support his explanation?
4. Whenever heat is added to ice it will melt, begin to bubble and make steam. What type of reaction is occurring? Use evidence to support your answer.
5.The equation below represents hydrogen and oxygen combining to form water.
2H2 + O2 —> 2H2O + energy
How is this chemical reaction similar to all chemical reactions?
6. What is the primary difference between a physical and chemical change?
7. “Just because a sign of a chemical change is seen, doesn’t mean that a chemical change is occurring,” yells Peyton to Fronmeka. Is Peyton correct? Explain.
8. Cassidie heats a sample of phosphorus. A flame is produced in the heating process. The product cooled into a black solid. A chemical reaction occurred. 9. What can be said of the product compared to the original sample of phosphorus?
9. Magnesium burns at 2220*C. Whenever it is burnt it produces magnesium oxide. While it is burning it produces a brilliant light, and it gives off heat. What is the best evidence that burning magnesium is a chemical reaction?
10. What can be done to a block of wood to make a physical change, and not a chemical reaction?
11.Brian is trying to design a simple test to determine if something is matter or not. He knows one of the properties of matter is that it takes up space. What is a simple test Brian can design to see if something takes up space?
12. Is air matter? Explain.
13. Lauryn explains that, “Light is matter because it can be seen. Furthermore,  you can feel sunlight on your skin.” Is Lauryn correct? Explain.
14. An unknown substance is not visible. It is made of millions of atoms but floats in the air. Would the unknown substance be classified as matter? Explain.
15. An unknown substance cannot be seen, but special machines are able to detect it. Is has no mass, but contains a large amount of energy. Would the unknown substance be classified as matter? Explain.
16. Jaiden boils some water for hot chocolate. The water starts to steam. What happens to the spacing between molecules as a liquid is converted into a gas?
17.Which state of matter has the most energy based off the movement of its particles?
18. Is a change in state a chemical reaction? Explain.
19. What happens to the amount of energy and spacing of the molecules as a substance changes from a liquid to a solid?
20. Timothy is trying to classify the state of matter of an unknown substance. Under a microscope, he notices that the particles are close together, but they have no regular arrangement. What state of matter is the unknown substance in?
21.The melting and boiling points of silver are 960*C and 1950*C, respectively. What is silver’s freezing point?
22. The melting and boiling points of silver are 960*C and 1950*C, respectively. If the sample of silver is currently at 800*C, what state of matter is it in?
23. Dakota freezes some milk in an attempt to make ice cream. What happens to the spacing between molecules as the liquid is converted into a solid?
24. Rachel says that any time she heats a substance, whatever state it may be in, that she is increasing the amount of energy it has. Is she correct? Explain.
25. An unknown substance needs to be classified as a solid, liquid, or gas. Its particles are close together and slide past each other. What state of matter is the substance in?
26. In order for a substance to change from gas to a liquid, what must happen to the movement of the molecules and the amount of energy?
27. The melting point and boiling point of an unknown substance is 25*C and 150*C, respectively. If the substance is currently at 70*C, what state of matter is it in?
28. The melting point and boiling point of an unknown substance is 25*C and 150*C, respectively. What is the condensation point of the unknown substance?
29. Substance A has a density of 5g/mL. Substance B has a density of 4.7g/cm3. Substance C has a density of 5.2g/mL. In what order from top to bottom would the following substances settle in a density column?
30. What two scientific tools are needed to solve for the density of a liquid?
31. “Pumice is a rock that floats in water,” explains Faith. “It has a density of 0.78g/mL.” Is Faith correct? Explain.
32. Joe is in Elmore Park’s science lab. He is trying to get a ping pong ball out of a tall, empty glass that is too small to reach in. He is not allowed to move the glass, or touch it with his hands. There is nothing available to stick in the glass such as a pencil. What can he do to get the ping pong ball out of the glass?
33. If a student knows the mass and density of an object, what other property can the student solve for?

Due Monday 12/11

1. What are three ways to reduce the strength of an electromagnet?
2. What materials are required to create an electromagnet?
3. What is the purpose of the rod in an electromagnet?
4. What are two differences between an electromagnet and a bar magnet?
5. Draw and label a picture of an electromagnet.
6. What are the two primary differences between an electromagnet and Earth’s magnetic field? T-chart it!
7. If I place a piece of metal on a magnet, where is it most likely to stick?
8. What is similar about the shapes of the magnetic fields of Earth, a bar magnet, and an electromagnet?
9. Why does the north pole of a magnet (found in a compass) point to the North pole of Earth? Give a full explanation.
10. What are three ways that the magnetic field of Earth, a bar magnet, and an electromagnet are similar?
11. What two materials actually create the electric current in an electric generator?
12. What can be used to show that electricity is being created in an electric generator?
13. What must you do with the magnet in order to create electricity?
14. What are three ways to reduce the amount of electricity created by an electric generator?
15. Draw an electric generator.
16. What are the two factors that affect the gravitational pull between objects?
17. Do all objects have gravity?
18. Josh and Tierra break up and walk away from each other, what happens to the amount of gravity between them?
19. Farrell lost seven kilograms. Everyone says it makes him more attractive. Speaking gravitationally, is Mr. Farrell more or less attractive?  Explain.
20. Which has more gravity if they are both put into the same size container, 100 grams of air or 100 grams of metal?
21. Does air have gravity? Explain.
22. Hailey takes her My Little Pony collection to Mars. The collection has a total mass of 15kg on Earth. What will the mass of the collection be on Mars?  Mars has 0.38 the gravity of Earth.
23. Will uses a triple beam balance for his autographed football. What is Will measuring?
24. If I said that something has 100 Newtons (N), what would that be a measurement of?
25. Ever year people set New Year resolutions to lose weight. Ethan had the great idea of going to the moon to lose weight. Will Ethan’s plan work?  Explain using evidence from your notes.
26. Ariah always complains that her book bag is too heavy. In order to prove her point, what tool could Ariah use?
27. Helen and Gina are arguing about weight and mass (they have no life). Gina says that they are the same, but Helen says they are not. Who is correct?  Explain using evidence from your notes.
28. Any time a measurement is given in grams, what is the measurement of?
29. If an object is taken to another planet in our solar system, which of its properties would change between mass and weight?
30. Tyler’s brain weighs 2 pounds (smaller than most humans). How much would his brain weigh on Jupiter that has 2.53 times the gravity of Earth?
31. Ever year people set New Year resolutions to get into a smaller pant size. Ethan had the great idea of going to the moon to be able to fit into smaller pants. Will Ethan’s plan work?  Explain using evidence from your notes.
32. What must happen for an orbit to be stable?
33. Why do all the planets orbit the sun rather than Earth?
34. Why does the moon orbit Earth instead of the sun, which is 330,000 more massive than the Earth?
35. If Saturn were to lose half of its mass, what would happen to its orbit around the sun?
36. Scientists have observed the moon accelerating in its orbit. What is happening to its orbit around Earth?
37. Why do all planets orbit the sun and not Jupiter, the largest planet in the solar system?
38. What two changes to the moon could occur that would cause it to crash into Earth?

Critical Thinking – Chemical reactions

 

1. Ginny observes that when milk and chocolate are mixed together that the milk changes color. She believes that in order to create chocolate milk a chemical reaction has occurred.  Is she right or wrong? 
2. Faith likes to play with glow sticks. She loves that when she bends a new glow stick it suddenly begins to glow.  What type of reaction is occurring in the glow stick, chemical or physical?  Provide evidence for your answer.
3. On the 4^th of July, Bartlett holds a firework display for the town. Micah attends each year with his family.  Micah explains that fireworks are an example of a chemical reaction.  What evidence can Micah use to support his explanation?
4. Whenever heat is added to ice it will melt, begin to bubble and make steam. What type of reaction is occurring?  Use evidence to support your answer.
5. The equation below represents hydrogen and oxygen combining to form water.

2H₂ + O₂ à 2H₂O + energy

                  How is this chemical reaction similar to all chemical reactions?

 

 

1. What is the primary difference between a physical and chemical change?
2. “Just because a sign of a chemical change is seen, doesn’t mean that a chemical change is occurring,” yells Peyton to Fronmeka. Is Peyton correct? 
3. Cassidie heats a sample of phosphorus. A flame is produced in the heating process.  The product cooled into a black solid.  A chemical reaction occurred.  What can be said of the product compared to the original sample of phosphorus?
4. Magnesium burns at 2220*C. Whenever it is burnt it produces magnesium oxide.  While it is burning it produces a brilliant light, and it gives off heat.  What is the best evidence that burning magnesium is a chemical reaction?
5. What can be done to a block of wood to make a physical change, and not a chemical reaction?
6. What type of reaction occurs when wood is set on fire? Be specific and explain.
7. Colin burns wood to cook food during one of his camping trips. What can be said of the product of the fire compared to the original wood?
8. Ariah adds salt to boiling water. Within seconds it completely dissolves.  Did a chemical reaction or physical change take place? 
9. Fuya watches as his mother lights a candle with a match. He tells her that when lighting the candle a chemical reaction takes place.  He mentions the various signs such as the reaction has a temperature change (it gets hotter), it gives off light, and it gives off a gas when the candle smokes a little.  Then he says, “Because of the signs I mentioned, I am certain that a chemical reaction took place.”  Is Fuya’s final statement in quotes to his mother accurate? 
10. Kayla is trying to physically change some milk without chemically changing it. What can Kayla do to the milk?
11. James balances a chemical equation for photosynthesis and for cellular respiration as shown below.

6CO₂ + 6H₂O + energy à C₆H₁₂O₆ + 6O₂ (photosynthesis)

C₆H₁₂O₆ + 6O₂ à 6CO₂ + 6H₂O + energy (respiration)

How are these two chemical reactions similar to all chemical reactions?

26. Chartavious tests an unknown substance.  When mixed with water, the    substance does not produce any ions.  What is the most likely pH level of the substance

27. Why are fossils considered to be the same age as the rock layer they are found in?

28.Which layer of rock is oldest in a rock column?

29.What would cause layers of rock to go missing in a geological column?

30. Draw an example of what a geological column would look like.

31. A scientist was digging for fossils along a rocky cliff. The scientist discovered trilobite fossils in rocks at two different depths in the cliff.  What can be determined about the fossils based on their locations.

36 .Which of the following is an example of relative age?

• 30,000 years ago
• in 300 CE
• in the beginning of the Jurassic Period
• after the extinction of T-Rex

Physical Change

Are you confused about the difference between chemical changes and physical changes and how to tell them apart? In a nutshell, a chemical change produces a new substance, while a physical change does not. A material may change shapes or forms while undergoing a physical change, but no chemical reactions occur and no new compounds are produced.

Physical Change Definition

A physical change is a type of change in which the form of matter is altered but one substance is not transformed into another. The size or shape of matter may be changed, but no chemical reaction occurs.

Physical changes are usually reversible. Note whether a process is reversible or not is not truly a criterion for being a physical change. For example, smashing a rock or shredding paper are physical changes that cannot be undone.

Contrast this with a chemical change, in which chemical bonds are broken or formed so that the starting and ending materials are chemically different. Most chemical changes are irreversible. On the other hand, melting water into ice (and other phase changes) can be reversed.

Physical Change Examples

No new chemical species forms in a physical change. Changing state of a pure substance between solid, liquid, and gas phases of matter are all physical changes, since the identity of the matter does not change.

Examples of physical changes include:

• crumpling a sheet or paper (a good example of a reversible physical change)
• breaking a pane of glass (the chemical composition of the glass remains the same)
• freezing water into ice (the chemical formula is not changed)
• chopping vegetables (cutting separates molecules, but does not alter them)
• dissolving sugar in water (sugar mixes with water, but the molecules are not changed and may be recovered by boiling off the water)
• tempering steel (hammering the steel does not change its composition, but does alter its properties, including hardness and flexibility)

Categories of Physical Changes

It's not always easy to tell chemical and physical changes apart. Here are some types of physical changes that may help:

Phase Changes - Altering the temperature and/or pressure can change the phase of a material, yet its composition is unchanged,

Magnetism - If you hold a magnet up to iron, you'll temporarily magnetize it. This is a physical change because it's not permanent and no chemical reaction occurs.

Mixtures - Mixing together materials where one is not soluble in the other is a physical change. Note the properties of a mixture may be different from its components. For example, if you mix together sand and water, you can pack the sand into a shape. Yet, you can separate the components of the mixture by allowing them to settle or by using a sieve.

Crystallization - Crystallizing a solid does not produce a new molecule, even though the crystal will have different properties from other solids. Turning graphite into a diamond doesn't produce a chemical reaction.

Alloys - Mixing together two or more metals is a physical change that is not reversible. The reason alloying is not a chemical change is because the components retain their original identities.

Solutions - Solutions are tricky because it may be hard to tell whether or not a chemical reaction has occurred when you mix together the materials. Usually, if there is no color change, temperature change, precipitate formation, or gas production, the solution is a physical change. Otherwise, a chemical reaction has occurred and a chemical change is indicated.

What Is a Chemical Reaction?

If liquid water is boiled, it is still water; likewise frozen water, or ice, is still water. Melting, boiling, or freezing simply by the application of a change in temperature are examples of physical changes, because they do not affect the internal composition of the item or items involved. A chemical change, on the other hand, occurs when the actual composition changes—that is, when one substance is transformed into another. Water can be chemically changed, for instance, when an electric current is run through a sample, separating it into oxygen and hydrogen gas.

Chemical change requires a chemical reaction, a process whereby the chemical properties of a substance are altered by a rearrangement of the atoms in the substance. Of course we cannot see atoms with the naked eye, but fortunately, there are a number of clues that tell us when a chemical reaction has occurred. In many chemical reactions, for instance, the substance may experience a change of state or phase—as for instance when liquid water turns into gaseous oxygen and hydrogen as a result of electrolysis.

HOW DO WE KNOW WHEN A CHEMICAL REACTION HAS OCCURRED?

Changes of state may of course be merely physical—as for example when liquid water is boiled to form a vapor. (These and other examples of physical changes resulting from temperature changes are discussed in the essays on Properties of Matter; Temperature and Heat.) The vapor produced by boiling water, as noted above, is still water; on the other hand, when liquid water is turned into the elemental gases hydrogen and oxygen, a more profound change has occurred.

Likewise the addition of liquid potassium chromate (K₂CrO₄) to a solution of barium nitrate (Ba[NO₃]₂ forms solid barium chromate (BaCrO₄). In the reaction described, a solution is also formed, but the fact remains that the mixture of two solids has resulted in the formation of a solid in a different solution. Again, this is a far more complex phenomenon than the mere freezing of water to form ice: here the fundamental properties of the materials involved have changed.

The physical change of water to ice or steam, of course, involves changes in temperature; likewise, chemical changes are often accompanied by changes in temperature, the crucial difference being that these changes are the result of alterations in the chemical properties of the substances involved. Such is the case, for instance, when wood burns in the presence of oxygen: once wood is turned to ash, it has become an entirely different mixture than it was before. Obviously, the ashes cannot be simply frozen to turn them back into wood again. This is an example of an irreversible chemical reaction.

Chemical reactions may also involve changes in color. In specific proportions and under the right conditions, carbon—which is black—can be combined with colorless hydrogen and oxygen to produce white sugar. This suggests another kind of change: a change in taste. (Of course, not every product of a chemical reaction should be tasted—some of the compounds produced may be toxic, or at the very least, extremely unpleasant to the taste buds.) Smell, too, can change. Sulfur is odorless in its elemental form, but when combined with hydrogen to form hydrogen sulfide (H₂S), it becomes an evil-smelling, highly toxic gas.

The bubbling of a substance is yet another clue that a chemical reaction has occurred. Though water bubbles when it boils, this is merely because heat has been added to the water, increasing the kinetic energy of its molecules. But when hydrogen peroxide bubbles when exposed to oxygen, no heat has been added. As with many of the characteristics of a chemical reaction described above, bubbling does not always occur when two chemicals react; however, when one of these clues is present, it tells us that a chemical reaction may have taken place.