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Awards Recognizing and celebrating excellence in chemistry and celebrate your achievements. Funding Funding to support the advancement of the chemical sciences through research projects. Lesson 2. Inquiry in Action. Lesson Overview for Teachers View the video below to see what you and your students will do in this lesson.
Objective Students will be able to explain that the density of a liquid has to do with how heavy it is for the sample size. Key Concepts A liquid, just like a solid, has its own characteristic density. The density of a liquid is a measure of how heavy it is for the amount measured. If you weigh equal amounts or volumes of two different liquids, the liquid that weighs more is more dense. If a liquid that is less dense than water is gently added to the surface of the water, it will float on the water.
If a liquid that is more dense than water is added to the surface of the water, it will sink. Summary In the previous lesson, students learned that density has to do with how heavy an object or substance is relative to its size, and that density determines whether an object sinks or floats.
In this lesson: As a demonstration, the teacher will compare the weight of an equal amount or volume of water and corn syrup so students can observe that corn syrup is more dense than water and sinks. Students will compare the weight of an equal amount or volume of water and vegetable oil and see that vegetable oil is less dense than water and floats.
Students add corn syrup to layered oil and water and see the corn syrup sinks below both the oil and water. Evaluation Download the student activity sheet PDF and distribute one per student when specified in the activity. Safety Make sure you and your students wear properly fitting safety goggles. Clean-up and Disposal Remind students to wash their hands after completing the activity. Engage 1. Do a demonstration to compare the density of corn syrup and water.
Place the cups on opposite ends of a balance. Expected results The corn syrup is heavier, which shows that it is more dense than water. Ask students: Since we weighed equal amounts and the corn syrup was heavier, is water or corn syrup more dense? Corn syrup is more dense than water. Predict what will happen if we pour the corn syrup into the water. Will the corn syrup float or sink when added to the water?
The corn syrup should sink in the water. Pour the colored corn syrup into the cup containing water to see if the corn syrup floats or sinks in the water.
Expected result It will sink. The corn syrup sinks in the water. Explore 2. Have students compare equal volumes of water and vegetable oil and test whether the oil floats or sinks when added to water. Thin oils have lower viscosity and pour more easily at low temperatures than thicker oils that have a higher viscosity. Thin oils reduce friction in engines and help engines start quickly during cold weather. Within reason, thicker oil maintains a better lubricant film between moving parts.
Some have even used thicker oil in a leaky engine to prevent oil from seeping out. But really, thicker oil is not good for your engine. The best grade of oil for your engine is the grade recommended by the manufacturer. The thickest motor oil readily available on the market is 40W This oil is made for antique cars with diesel engines that burn oil excessively.
The thickness of oil is more commonly referred to as viscosity grade. The higher the number, the more resistance the oil exhibits. While both are low-temperature grade oils, 10W40 is thicker at high temperature; therefore, better to use in warm weather. If you use w instead of 5-w specified by the manufacturer then the viscosity of w used by you will be higher and oil thicker than what is specified during winters.
Similarly the oil viscosity will be higher and oil thicker than specified during summers. Not only that, but the engine will waste energy pumping the thicker motor oil, reducing fuel economy. Begin typing your search term above and press enter to search.
Press ESC to cancel. Even though the molecules that make up alcohol contain a heavier oxygen atom, alcohol is less dense than oil because alcohol molecules do not pack closely together. The American Chemical Society is dedicated to improving lives through Chemistry.
Chapter 3, Lesson 5 Multimedia Oil Oil is more dense than alcohol, but less dense than water. Water Water molecules are packed more closely together than the long molecules that make up oil.
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