Gay-Lussac’s Temperature and Volume Changes in a Gas Law (Charles’s Law)

Lesson Overview

In this activity students collect data about the temperature and volume of a confined gas. From these data students can determine whether a mathematical relationship exists between the volume of a gas and its temperature. The effects of varying temperature of a fixed mass of gas at constant pressure will be observed and measured. Collected data will be plotted on a graph (computer- or calculator-based graphing) from which a relationship may be determined. Can it be expressed mathematically?

Student Ability Level and Grouping

This activity is appropriate for all levels of chemistry class, for students working in pairs.

Expected Student Background and Skills

Prior to carrying out the activity, students should already understand basic math skills, including graphing; direct and indirect relationships between sets of data; the meaning of ratios and calculating slope values from a graph; and the idea of a constant as found in a slope. They should also be able to accurately read an analog thermometer, if used, rather than a digital thermometer.

Time and Materials Required

This activity will require two 45-minute periods to collect data as well as to evaluate the reliability of the data. During this time students will also need to perfect their skills in accurately reading an analog thermometer and a capillary tube with a moving plug.

Non-consumables

  • 12 analog thermometers
  • 24 capillary tubes (4-mm tube, 12 to 14 cm in length)
  • 12 centimeter rulers
  • 24 beakers (400 mL)
  • 24 rubber bands (small, to fit around thermometer and capillary tube together)

Consumables (see advanced preparation)

  • Ice
  • 250 mL of #30 non-detergent motor oil (or mineral oil with dye added; also dibutyl pththalate)

Learning Objectives

After completing this activity, students should

  • understand the relationship between temperature changes to a confined gas and the resulting volume change of that gas;
  • understand the basis for the mathematical relationship between the change in temperature and the resulting volume of a gas;
  • be able to graph the data for temperature and volume of a gas and interpret the relationship shown;
  • be able to determine the temperature at which the volume of a gas is zero;
  • understand the use of a different temperature scale (absolute or Kelvin);
  • be able to accurately predict the new volume of a gas that results from a temperature change of a known volume of a gas in an expandable container; and
  • understand that another variable, pressure of a gas, must be kept constant to observe effects of temperature on the volume of a confined gas.

National Science Education Standards

Unifying Concepts and Processes

  • Evidence, models, and explanations
  • Change, constancy, and measurement

Science as Inquiry

  • Understandings about scientific inquiry
  • Abilities to do scientific inquiry

Physical Science

  • Conservation of energy and increase in disorder
  • Interactions of energy and matter

History and Nature of Science

  • Science as a human endeavor
  • Nature of scientific knowledge
  • Historical perspective

 

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