Get another small piece of dry ice from your teacher. I walk around making sure that students are consistently stirring and that all students in the group are simultaneously recording data. These questions are designed to connect the students' experience at the lab bench to the theoretical underpinnings of phase change. Blauch of Davidson College presents several interactive experiment simulations on topics such as equilibrium, kinetics, crystal structure, phase changes, gases, and more. The user controls the action of a piston in a pressure chamber filled with an ideal gas, illustrating relationships between temperature, volume, pressure, and molecular weight. To help reinforce the concepts that we learned in the lesson I have students perform a heat of fusion lab where they calculate the heat of fusion of ice.
Students will prepare test tube models of water-contaminated fuel tanks and explore the effect of adding different types of fuel line antifreeze. There are twelve events on this quiz. It is intended for students who already have functional knowledge of basic kinetic molecular theory. Managers are feeling the pressure. Phase changes happen when certain temperatures are reached.
In liquids, they have higher energy, are more loosely connected, and can slide past one another; some molecules may get enough energy to escape into a gas. The process of when a liquid becomes a gas is called either boiling or evaporating. Still, the fact that our graph stays relatively cold until all the ice melts and the evens out at the boiling point is a close approximation of the textbook example of a phase change graph. Get the bubble solution and practice blowing bubbles with the straw. Students also do not recognize particles as building blocks, but instead believe that they are continuous substances.
This lesson can be used to bolster concepts about miscibility, density, intermolecular forces, phase changes freezing , and colligative properties freezing point depression. What is the theory that explains all matter is made up of particles that are in constant motion? I also show them that in fact water can get hot--up to 100 oC. They should revisit the hypothesis they wrote prior to the lab. As our body sweats, what phase change occurs? Dry ice is about twice as heavy as regular ice. Now is the time to warm the water. As I go over these calculations I have students perform practice questions on slides 12 and 14.
Typically, we have been working toward the next review with a fairly short horizon. In gases, the atoms or molecules have still more energy and are free of one another except during occasional collisions. This is because the heat is being used to change the phase of the substance. When water goes directly from a gas to a solid, it is known as deposition. This is shown when water vapor from the air changes directly into its solid form known as frost.
Any water that had evaporated would condense back into a liquid as it cooled. When all of the dry ice has changed to vapor, gently blow bubbles and get them to land in the beaker. This leads to an interesting conversation about how boiling is a form of evaporation, and evaporation is a cooling event. Unit Test: This test has 44 multiple choice questions. This leads to an interesting conversation about how boiling is a form of evaporation, and evaporation is a cooling event. In our experiment today, we discovered that mass is not gained or lost during phase changes.
For each square, a student can either agree with the square based on the depiction that they have, or the student can suggest a modification based on what the directions indicate. In order to do this, you have to add an enormous amount of energy to the gas in order to free up the electrons from the atoms. Place the dry ice in a film canister and put on the lid. Place it on your table. I am very vigilant about safety issues.
When a liquid becomes a solid, heat is removed from a substance and it is known as freezing. . The answers I expect are found in the. What do you think is happening at the molecular level? Step 2: Measure out 250 milliliters of water or any amount really, as long as you note it down and put it inside the cup. It may be a good idea to write an abbreviation next to the notch to make sure you know which mark is which. When all of the dry ice has changed to vapor, gently blow bubbles and get them to land in the beaker.
Extensions One way to reinforce this concept is to give each student a balloon and a length of string and tell them: Tonight you should take this home and blow up and tie off the balloon. What is the relationship between the temperature and time during each phase change? When a gas becomes a liquid, heat is removed from a substance and it is known as condensation. When a gas becomes a liquid, heat is removed from a substance and it is known as condensation. Step 3: Measure the mass of the cup with the water inside. During phase changes, even though heat is added or removed, the temperature does not change. It has a higher density.