Welcome to iSci. In this module you will learn about the composition of dry and wet salt, and you will be able to interact directly with virtual salt molecules in motion-controlled simulations. Let’s get started! Tap on the screen to go to your first activity.
In this first activity you will get a good idea of what common salt found in salt shakers really looks like if you were able to see it up close. To begin this activity, aim your tablet screen at the salt shakers found on Poster 1.
If you do not have access to the poster, you can still watch the animation by pressing the play button on the next screen.
What did you notice about the composition of salt? Once you answer the question in your Lab Notes, you will be able to continue.
On the next screen, you will be asked to describe the form salt takes, so pay close attention.
Let's see what you have learned from the video. Answer the following question by selecting all of the answers you think are correct. You will be able to continue to the next part of the module once you have completed the quiz successfully.
The salt you see in the salt shakers is known as refined salt or common table salt. What form did this salt take in the video?
A powder is a dry, bulk solid composed of a large number of very fine particles that may flow freely when shaken or tilted. Powders are a special sub-class of granular materials.
A crystal is a solid material whose constituent atoms, molecules, or ions are arranged in an ordered pattern extending in all three spatial dimensions.
A fluid is a substance that continually deforms (flows) under an applied shear stress. The term "fluid" includes both the liquid and gas phases of matter.
Glass is an amorphous (non-crystalline) solid material that exhibits a reversible transition from a hard and relatively brittle state into a molten or rubber-like state.
Oops! Please review your answer and try again to continue. Remember that more than one answer may be correct.
Well done! Continue to Activity 2 by tapping the arrow.
Now, let’s think about what salt is. The animation has shown you that dry salt takes the form of a crystal, but this is not all that salt is. It is comprised of smaller parts that help salt to take the form of a crystal. Let’s go inside a crystal of salt. To begin this activity, aim your tablet screen at the salt crystal found on Poster 2.
If you do not have access to the poster, you can still watch the animation by pressing the play button on the next screen.
Now that you have gone deeper into a salt crystal, what did you notice about the composition of salt? Once you answer the question in your Lab Notes, you will be able to continue.
On the next screen, you will be asked to describe the form salt takes, so pay close attention.
Open your Lab Notes, and write a sentence that describes the salt crystal you see in the image. Once you answer the question in your Lab Notes, you will be able to continue. Here are two questions you can that will help you with your description:
- What is the shape of the objects in the image?
- Why do you think they are different sizes?
Refined salt or common table salt is mainly composed of a compound called sodium chloride. In fact, common table salt is usually 97-99% pure sodium chloride. The chemical formula of this compound is NaCl (Na = sodium, Cl = chloride), which represents equal portions of sodium and chloride.
Look at the image of the salt crystal. What do you notice about it?
Write one sentence that describes the way the salt crystal is organized in the image. Make a guess – that is, hypothesize – what is causing the crystal to be arranged in this way?
Once you answer the question in your Lab Notes, you will be able to continue.
In the crystal structure, the larger Cl ions are arranged in a 3D grid. The smaller Na ions are all found in their own grid within the gaps between the Cl ions. Together, they are known as a face-centered cubic lattice.
The term face-centered cubic lattice is an important one. Follow the link to Wikipedia and study this term. Paraphrase the information you find. Record your paraphrased definition in your Lab Notes, and then you will be able to continue.
This arrangement of two overlapping cubic grids makes a cubic crystal. Answer the question by selecting all of the answers you think are correct. You will be able to continue to the next part of the module once you have completed the quiz successfully.
Let’s think a bit more about the word cubic in the term face-centered cubic lattice. What is a cube? Below are four possible characteristics of a cube. Choose all that are correct.
Three-dimensional space is a geometric 3-parameters model of the physical universe (without considering time) in which we exist.
Volume is the quantity of three-dimensional space enclosed by some closed boundary, for example, the space that a substance or shape occupies or contains.
In elementary models of space, height may indicate the third dimension, the other two being depth and width.
In geometry, a square is a regular quadrilateral. This means that it has four equal sides and four equal angles.
Oops! Please review your answer and try again to continue. Remember that more than one answer may be correct.
Well done! Continue to Activity 3 by tapping the arrow.
In chemistry, salt is an ionic compound because sodium and chloride are both ions. An ionic compound usually consists of a positively-charged metal ion (e.g. sodium) from the left side of the periodic table, and a negatively-charged nonmetal ion (e.g. chloride) from the right side.
Go to Wikipedia and look up the term ion. Paraphrase the information you find. Record your paraphrased definition in your Lab Notes, and then you will be able to continue.
In a cubic crystal, each ion is surrounded by six ions of the opposite charge. In the case of the salt crystal, six sodium ions surround each chloride ion, and six chloride ions surround each sodium ion.
In your Lab Notes, write a hypothesis about why the cubic crystal is arranged in this way. Why do you think the number six is important? Why not a different number? Once you complete your hypothesis, you will be able to continue.
Using your Lab Notes, hypothesize why the sodium and chloride ions remain in the cube structure and do not fall apart. What causes them to remain in a 3D grid arrangement? Once you complete your hypothesis, you will be able to continue.
The salt crystal holds together as a cube because the Cl ions have a negative charge, and the Na ions have a positive charge. The opposing charges attract each other very strongly, holding the crystal together. This is why salt has such a high melting point - over 800°C! It takes a lot of energy to break apart those ionic bonds.
Now, continue to Activity 4 by tapping the arrow.
Now let's see if we can understand sodium and chloride ions in the salt molecule better. We will interact with a virtual salt molecule using the Kinect and Wiimote. You will be able to manipulate the molecules in order to move them around and see them from various angles.
Let's start by exploring the control that you have over the virtual molecule. Press and hold left on the WiiMote directional pad, and then press and hold the B button. Now, walk back and forth in front of the molecule. What did you notice about the molecule's movement? Use your Lab Notes to record your observations, and then you will be able to continue.
Let's explore the molecule further by rotating it. Press and hold up on the WiiMote directional pad, and then press and hold the B button. Now, slowly wave your free hand back and forth. What did you observe about the symmetry of the cubic lattice? Use your Lab Notes to record your observations, and then you will be able to continue.
Now, let's examine the molecule from different points of view. Press and hold down on the WiiMote directional pad, and then press and hold the B button. Now, look around and under the molecule by moving your head. What did you observe about the pattern of the cubic lattice? Use your Lab Notes to record your observations, and then you will be able to continue.
Now, let's get a very close look at the molecule by scaling it. Press and hold right on the WiiMote directional pad, and then press and hold the B button. Now, slowly move your free hand toward and away from the molecule. How would you describe the organizational structure of the sodium and chloride ions? Use your Lab Notes to record your observations, and then you will be able to continue.
Now, you will be assessed on what you have learned in Activities 1-4. Tap the arrow to continue.
As you noticed from looking at the salt molecules, something is holding the molecules together. You have seen how this causes the cubic crystal arrangement. Now you will experience firsthand what that "something" is by feeling it with the Falcon Controller.
Now, you will explore what happens to solid salt when it comes into contact with water. Aim your tablet screen at the salt in water found on Poster 3.
If you do not have access to the poster, you can still watch the animation by pressing the play button on the next screen.
How does the appearance of salt change when it is poured into water? Once you answer the question in your Lab Notes, you will be able to continue.
Let's see what you have learned from the video. Answer the following question by selecting all of the answers you think are correct. You will be able to continue to the next part of the module once you have completed the quiz successfully.
Remember your experience with salt in water. You drop it in, and it eventually disappears. Why? What do you think happens to it?
Can you really see any salt crystals at the very end of the video?
Are the small salt crystals still partially visible as they break down in water?
If you viewed the mixture with a microscope, you still would not see small pieces of salt.
Water is sometimes called the universal solvent because it is so good at dissolving other substances.
Oops! Please review your answer and try again to continue. Remember that more than one answer may be correct.
Well done! Now, continue to Activity 6 by tapping the arrow.
As you've seen from the dry salt module, salt crystals are small but strong. Dry salt has a melting point of 800°C, so it takes a lot of energy to melt it and break the crystal. Compare that to butter, which melts at about 40°C (in your hand). A tin can melts around 230°C. Even an aluminum soda can melts easier than salt at around 660°C.
Now, let's dive deeper into a solution of dissolved salt in water. Aim your tablet screen at the salt and water molecules found on Poster 4.
If you do not have access to the poster, you can still watch the animation by pressing the play button on the next screen.
How are the salt and water molecules organized in the solution? Once you answer the question in your Lab Notes, you will be able to continue.
Let's examine the process of dissolution. View the simulation of a small salt crystal in water, and watch how the water disassembles the crystal. Try altering the speed of the simulation to get a closer look at the action.
Go to Wikipedia and look up the term dissolution. Paraphrase the information you find. Record your paraphrased definition in your Lab Notes, and then you will be able to continue.
In your Lab Notes, write some examples of salt dissolved in water. Where have you seen it or read about it? Give references with your examples.
Now let's look at how the molecules of salt and water behave inside the solution. The upcoming interactive challenge uses the Falcon and Kinect controllers to simulate the molecular forces at work.
From the solution of salt dissolved in water, can you reassemble the salt crystal as it appeared at the beginning of the module? There may be more than one way to do it. Be creative, and take notes on everything you try so your friends can try it too!
Using your Lab Notes, answer the following questions. What did you learn from the challenge? Did you manage to reconstruct a salt crystal from the solution? If so, how?
Using your Lab Notes, answer the following questions. If you could not get a crystal back, why do you think that happened? What did you try? Which methods worked well, and which did not work?
Now, you will be assessed on what you have learned in Activities 1-7. Tap the screen to continue.
The WiiMote has several buttons that allow you to control the molecule in virtual space. Tap the highlighted buttons for a description of their functions.
Holding the WiiMote in your left hand, stand about 8-10 feet from the Kinect device. Make sure that you are closest to the device, and that no one is directly behind or beside you. This way, the Kinect will accurately detect your motion.
