Temperature Affects Density

Learning Resource Type

Classroom Resource

Subject Area

Science

Grade(s)

8

Overview

In this lesson, students place hot and cold colored water into room-temperature water. They observe that the hot water floats on the room-temperature water and the cold water sinks. Students will combine the concepts of temperature, molecular motion, and density to learn that hot water is less dense than room-temperature water and that cold water is denser.

Students will be able to explain, on the molecular level, how heating and cooling affect the density of water.

Science (2015) Grade(s): 8

SC15.8.4

Design and conduct an experiment to determine changes in particle motion, temperature, and state of a pure substance when thermal energy is added to or removed from a system.

UP:SC15.8.4

Vocabulary

  • Particle motion
  • Temperature
  • State [of Matter]
  • Pure substance
  • Thermal Energy
  • Kinetic Energy
  • System

Knowledge

Students know:
  • Changes in particle motion of a pure substance occur when thermal energy is added to or removed from a system.
  • Changes in temperature of a pure substance occur when thermal energy is added to or removed from a system.
  • Changes in state of a pure substance occur when thermal energy is added to or removed from a system.

Skills

Students are able to:
  • Identify the phenomena under investigation, which includes changes in particle motion, temperature, and state of a pure substance when thermal energy is added to or removed from a system.
  • Identify the purpose of the investigation, which includes determining changes in particle motion, temperature, and state of a pure substance when thermal energy is added to or removed from a system.
  • Develop a plan for the investigation individually or collaboratively.
  • Describe factors used in the investigation including appropriate units (if necessary), independent and dependent variables, controls and number of trials for each experimental condition.
  • Perform the investigation as prescribed by the plan.
  • Use data from the investigation to provide an causal account of the relationship between the addition of removal of thermal energy from a substance and the change in the average kinetic energy of the particles in a substance.

Understanding

Students understand that:
  • Adding or removing thermal energy from a system causes changes in particle motion of a pure substance.
  • Adding or removing thermal energy from a system causes changes in temperature of a pure substance.
  • Adding or removing thermal energy from a system causes changes in state of a pure substance.

Scientific and Engineering Practices

Planning and Carrying out Investigations

Crosscutting Concepts

Systems and System Models
Science (2015) Grade(s): 8

SC15.8.5

Observe and analyze characteristic properties of substances (e.g., odor, density, solubility, flammability, melting point, boiling point) before and after the substances combine to determine if a chemical reaction has occurred.

UP:SC15.8.5

Vocabulary

  • Characteristic properties (e.g., odor, density, solubility, flammability, melting point, boiling point)
  • Substances
  • Chemical reaction

Knowledge

Students know:
  • Each pure substance has characteristic physical and chemical properties that can be used to identify it.
  • Characteristic properties of substances may include odor, density, solubility, flammability, melting point, and boiling point.
  • Chemical reactions change characteristic properties of substances.
  • Substances react chemically in characteristic ways.
  • In a chemical process, the atoms that make up the original substances are regrouped into different molecules, and these new substances have different properties from those of the reactants.

Skills

Students are able to:
  • Observe characteristic physical and chemical properties of pure substances before and after they interact.
  • Analyze characteristic physical and chemical properties of pure substances before and after they interact.
  • Analyze the properties to identify patterns (i.e., similarities and differences), including the changes in physical and chemical properties of each substance before and after the interaction.
  • Use the analysis to determine whether a chemical reaction has occurred.

Understanding

Students understand that:
  • Observations and analyses can be used to determine whether a chemical reaction has occurred.
  • The change in properties of substances is related to the rearrangement of atoms in the reactants and products in a chemical reaction (e.g., when a reaction has occurred, atoms from the substances present before the interaction must have been rearranged into new configurations, resulting in the properties of new substances).

Scientific and Engineering Practices

Analyzing and Interpreting Data

Crosscutting Concepts

Patterns

CR Resource Type

Lesson/Unit Plan

Resource Provider

American Chemical Society

License Type

Custom
https://www.acs.org/middleschoolchemistry/lessonplans/chapter3/lesson6.html

Custom License Type (URL)

https://www.acs.org/content/acs/en/terms.html

Accessibility

Video resources: includes closed captioning or subtitles

Comments or Notes

A video that explains how to teach the lesson is provided.

Approved Date

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