Exam (elaborations) GIZMOS Student Exploration Diffusion

Exam (elaborations) GIZMOS Student Exploration Diffusion Vocabulary: absolute zero, controlled experiment, diffusion, dynamic equilibrium, Kelvin scale, kinetic energy Prior Knowledge Question (Do this BEFORE using the Gizmo.) Have you ever smelled microwave popcorn? The oddly enticing scent can fill a whole house. How do you think the smell of popcorn spreads through the air? Gizmo Warm-up Smells are carried by tiny particles that move through the air. The Diffusion Gizmo shows gas particles in a chamber that is divided into two regions by a partial wall. Click Play ( ) and observe. 1. Describe the motion of the gas particles. 2. Over time, what is happening? This process, in which particles move from an area of high concentration (region A) to an area of low concentration (region B), is called diffusion. 3. Select the BAR CHART tab, and observe the chart for a few minutes. After the first 30 seconds or so, how much do the numbers of particles in each region change? Reproduction for educational use only. Public sharing or posting prohibited. © 2020 ExploreLearning™ All rights reserved Name: Date: Tuesday, February 16, 2021 Through the process of diffusion, the particles of the smell spreads around the house by bouncing off the walls, traveling from a high concentration to a low. The motion of the gas particles in region A are moving fast and bounce back off the partial wall until they get into region B. They still continue to bounce back and forth into region A and B. The amount of gas particles in each region is starting to balance out with each other gradually. The number of particles in region A is gradually lowering from 50 to 38 in just around 30 seconds. At the 30 seconds mark region A has 38 particles and region B has 12. Just by this observation, I can tell that around the 60 second mark the number of particles in region A and B are going to be very similar. GIZMOS Student Exploration Diffusion When the numbers don’t change much, the particles are said to be in dynamic equilibrium. 4. Click Pause ( ), and select the GRAPH tab. What does the graph tell you about the number of particles in region A? Introduction: In this Gizmo, temperature is measured on the Kelvin scale. On this scale, 0 K represents absolute zero, the coldest possible temperature. Water freezes at 273.15 K (0 °C), and water boils at 373.15 K (100 °C). Question: How does temperature affect the rate of diffusion? 1. Observe: Set the temperature (Temp.) to 100 K, and press Play. Observe the motion of particles. Click Reset. Then set the temperature to 600 K, click Play, and observe. How does the temperature of the gas relate to the motion of the particles? The temperature of a gas is a measure of the average kinetic energy of a set of particles. Kinetic energy (KE) depends on the velocity and mass of the particles (KE = mv 2 / 2). 2. Form hypothesis: How do you think temperature will affect the rate of diffusion? 3. Experiment: Click Reset. Set the Wall to 50%, x in A to 100, y in B to 0, Temp. to 100 K, and Particle mass to 15 amu (atomic mass units). Select the TABLE tab. Press Play. Click Pause when x in A first reaches 55% or below. Record this Time to reach equilibrium in the left table below. Reproduction for educational use only. Public sharing or posting prohibited. © 2020 ExploreLearning™ All rights reserved When I clicked pause at 30 seconds, I can tell that number of particles in region A is constantly decreasing for the most part. Throughout the 30 seconds the number of particles in region A do increase a few times; overall as seconds go by the number of particles in region A are decreasing. Activity A: Temperature and diffusion Get the Gizmo ready: ● Click Reset ( ). ● Set the Wall to 100%. When the temp is set to 100k the particles move around slower compared to when I set it to 600k, they move around faster. Therefore the hotter the temp is, the faster the particles move. When the temperature rises, the kinetic energy of the particles increase. The faster motion of the particles causes them to diffuse at a faster rate. Therefore, when the temperature is higher, the faster the particles will diffuse compared to a lower temperature. Repeat four more times at 100 K, and then run five trials with the temperature set to 600 K. Temp = 100 K experiment Temp = 600 K experiment 4. Calculate: Find the average time to reach equilibrium for each experiment: 5. Draw conclusions: Compare the average times to reach equilibrium for each temperature. 6. Extend your thinking: Why do you think the experimental results were different for each trial? 7. On your own: In our lives, we rarely experience temperatures that are above 373 K (100 °C) or below 273 K (0 °C). Investigate how much diffusion rates differ between these two temperatures. Describe the results of your experiments below. Reproduction for educational use only. Public sharing or posting prohibited. © 2020 ExploreLearning™ All rights reserved Trial Time to reach equilibrium 1 202 (s) 2 420 (s) 3 224 (s) 4 412 (s) 5 298 (s) Trial Time to reach equilibrium 1 77 (s) 2 110 (s) 3 129 (s) 4 112 (s) 5 105 (s) A. Average time to reach equilibrium at 100 K: 311 (s) B. Average time to reach equilibrium at 600 K: 107 (s) A. How did temperature affect the rate of diffusion? When the temperature is higher, the faster the particles will diffuse compared to a lower temperature B. Why do you think this was the case? When the temperature rises, the kinetic energy of the particles increase. The faster motion of the particles causes them to diffuse at a faster rate. When I set the temperature higher the particles diffuse quicker because the higher the temperature is, the particles of kinetic energy increase. When the temperature is lower, the particles take more time to diffuse because the lower the temperature is, the particles of kinetic energy decrease. The average rate when I set the temperature around 373k is 123 (s) compared to when I set it to 273k which is 103 (s). The diffusion rates are quite similar since they are only 100 K apart. Introduction: The Diffusion Gizmo allows you to manipulate five variables: the Wall, the number of x particles in region A, the number of y particles in region B, the temperature, and the Particle mass. Question: How do factors other than temperature affect the rate of diffusion? 1. Choose a variable: Pick a variable to investigate. Which one did you choose? 2. Form hypothesis: How do you think this variable will affect rates of diffusion? 3. Set up experiment: In a controlled experiment, only one variable is manipulated, or changed. Set up your experiment so that there is just one difference between set-up A and set-up B. List the Gizmo settings you will use for each set-up belo