Mini-Lab: Kinetic Theory

Name: __________________________________ Date: _____________________________ Mini-Lab: Kinetic Theory Introduction Purpose: The purpose of this investigation is to explore how particles behave in matter and how temperature and energy affect particle motion. Through a series of observations and experiments, students will gather data to investigate the relationship between temperature, energy, and motion. Materials: Paper towels, Thermometer, Safety goggles ●​ Experiment #1: Beakers, Hot water, Cold water, Food coloring ●​ Experiment #2: Clear cups, Hot water, Cold water, Food coloring, Plastic Divider ●​ Experiment #3: Paper towel, isopropyl alcohol, water Background: The Kinetic Molecular Theory (KMT) explains matter in terms of the motion of its particles. All matter is made of tiny particles that are in constant motion. In solids, particles vibrate in place; in liquids, particles move past one another; and in gases, particles move freely. Temperature is a measure of the average kinetic energy of particles. Kinetic energy is the energy of motion. As temperature increases, particle motion increases; as temperature decreases, particle motion slows. One observable result of particle motion is diffusion, the spreading of particles due to random motion. Diffusion occurs without stirring and happens faster at higher temperatures because particles move more quickly. Temperature also affects density. As temperature increases, particles spread farther apart, decreasing density. This can affect whether fluids mix or form layers when combined. Although particles cannot be seen directly, their motion can be observed indirectly. Under a microscope, small particles in water appear to move randomly due to collisions with constantly moving water molecules. This provides evidence that particle motion is continuous in all states of matter. In this experiment, diffusion, fluid layering, and microscopic observations are used to investigate the relationship between temperature, energy, and particle motion. Pre-Lab Questions 1.​ What causes something to float or sink? Density causes something to float or ink 2.​ What do you think temperature tells us about the particles in a substance? It can tell us how fast they are moving 3.​ If one substance is hot and another is cold, what do you think is different about their particles? The difference between their particles would behow far apart they are and the speed at which they move 4.​ Compare the movement of particles in ice, liquid water, and water vapor. In ice the particles cant move around each other, in liquid water they move faster and can pass each other, in water vapor they move very fast randomly Observations Experiment #1: Food coloring will be added to hot water and cold water without stirring. 5.​ What happens to the food coloring in each cup over time? In the hot cup the die spreads around the entire cup, moving around and seperating through the whole thing In the cold cup it stays pretty compact and all moves together, also sinking to the bottom 6.​ Which spreads faster? The dye in the hot water Experiment #2: Hot and cold water will be carefully layered on top of each other. 7.​ What happens when cold water is placed on top of hot water? They mix quickly, and the red goes upwards. 8.​ What happens when hot water is placed on top of cold water? They do not mix because the cold water has more closely kept together particles that are kept down by gravity 9.​ Which setup mixes more? Which stays separated? Cold stays separate, the warm mixes Experiment #3: You will observe the evaporation of water and isopropyl alcohol at room temperature. 10.​How long did it take the isopropyl alcohol to evaporate? Aproxamintly 5 seconfs 11.​How long did it take the water to evaporate? It was still not evaporated at the end of the video Analysis Experiment #1: 12.​Why does the dye spread out even though the water is not being stirred? Bc the particles are in motion already, so we do not need to stir it 13.​How does temperature affect how quickly the dye spreads? Higher temp caused dye to spread fast but in cold it stays more together and more compact 14.​What must be happening at the particle level to explain your observations? The higher the temperature the higher the kinetic energy, so the water particles will move faster, also moving the dye particlers which spreads them about the container Experiment #2: 15.​Apply the concept of density to explain what is happening. Hot water is less dense then cold water bc cold is more dense and together, but hot is lighter 16.​How does temperature affect particle spacing and density? When the temp is higher particles move faster and spread more apart which makes it less dense too 17.​How does particle motion help explain why one setup is stable and the other is not? The stable setup is when the hot is on top bc the cold particles are more dense so gravity keeps it at the bottom. That alo shows why when cold is at the top gravity brings it down, causing them to mix togehter Experiment #3: 18.​Which liquid evaporated faster? isopropyl alcohol 19.​From your observations, which liquid do you infer has greater average particle motion? Explain your reasoning using specific evidence from what you saw. The isopryoal alcohol has greater average particl motion because it evaproated significantly faster Post-Lab Questions 20.​Why does dye spread in still water, even though it is not being mixed? Bc the partlceds are constantly in motion so they mix aroundt he dye particles 21.​Which has faster-moving particles: hot water or cold water? How do you know? Hot water because they mixed a lot faster then in the cold 22.​What does temperature tell us about the particles in a substance? That temperature measures the ave. kinetic energy/ partice speed 23.​What happens to particle motion when energy is added? The particles move faster 24.​Complete each statement using words like faster, slower, more, or less. Then briefly explain why in terms of particle motion. a.​ Higher temperature → faster particle motion because the particles will have more kinetic energy b.​ Lower temperature → slower particle motion because the particles will have less kinetic energy c.​ More energy → more particle motion because the more energy there is the more the particles move d.​ Less energy → less particle motion because the less energy there is the less they move 25.​How are temperature, energy, and particle motion related? The higher temperature adds energy to the particles, therefore speeding them up, and the opposite is true for lower temperature.