Summer Research Program for Science Teachers

The Charles= Law

How does the volume of a given quantity of air kept under constant pressure vary with its temperature?

Gusteau Duclos- Samuel Tilden HS - 1996

NAME:______________________

LAB GROUP: I II III IV V VI VII

CLASS PERIOD #:

PARTNERS:__________________

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ABSTRACT

DATE DUE:____________________

DATE REC:_______ GRADE_____

LATE POINTS_____

FINAL SCORE_____

CHECK LIST FOR LAB#15: DO YOU HAVE

__The graph;

__Filled data tables;

__An abstract including:

A statement of the reason for this lab session.

A statement describing the method.

A statement of your result.

1.- PROBLEM

How does the volume of a given quantity of air kept under constant pressure vary with its temperature? [Content Standard B- Properties of matter]

2.- THEORY

The condition of any substance in the gaseous state is determined by its pressure, its volume and its temperature. The equation of state describes the relationship between those 3 parameters under the assumption of perfect gas, that means there is no interaction between gas molecules considered to be mass points. In the study of gas behavior, most of the time, one parameter is kept constant and the relative variation of the other two with respect to one another is observed. If the pressure of a gas is kept constant and its temperature is decreased, its volume also decreases. This law is known as the Charles= law.

V is the volume of the gas

T is its temperature in degree Kelvin

The pressure is kept constant.

3.- MATERIALS

Syringe with cap at one end; piston to fit syringe; wood block to fit syringe and support masses; a base block to support the apparatus; set of masses; -40oC to 100oC thermoneter; dry ice; petroleum jelly; glass stopper.

4.- PROCEDURE AND DATA COLLECTION

a) Measure the diameter of the syringe and record it in the provided space in page 2.

b) Lubricate the interior wall of the syringe with petroleum jelly.

c) Insert the thermometer in the glass stopper, and place them in the side opening of the syringe.

d) Insert the piston in the top end of the syringe and place the cap at the other end as illustrated by the last page figure.

e) Place this syringe on the base block with the cap facing down and position the wood block as shown.

f) Place an appropriate mass as shown and record it in the provided space.

g) Adjust the height of the piston so that it is just far enough to support the wood block and the mass by removing the cap temporarily if necessary and/or choosing another mass.

h) In the first row of the table below record the air temperature and the volume of trapped air in the syringe.

i) Using the plastic gloves, put dry ice all around the syringe leaving just enough space to see the level of the piston.

j) Every minute, and for 20 minutes, read and record the temperature and the volume of the trapped air. [Content Standard Unifiying Concepts- Change, constancy, and measurement]

k) Put the remaining dry ice into the container, clean your tables.

5.- QUESTIONS

I.

a) Plot the Volume - Temperature graph (be sure to use the average values for both the temperature and the volume)

b) Draw the best fit line

c) Find the slope of this line.

d) What is the physical meaning of this slope?

e) Using this graph to explain what happens to the volume of the trapped air 1)when the temperature decreases 2)when it increases. [Content Standard Unifying Concepts- Evidence, models, and explanation]

f) At which temperature will the volume of the air be equal to zero?

g) Explain why this is a theoretical consideration. [Content Standard A- Formulate and revise scientific explanations]

f) On the figure of the last page, draw vectors to represent all forces that act upon the piston (Do not forget the frictional force)

II.

a) Why is it better to lubricate the interior wall of the syringe?

b)Why is it important to put a mass on the piston?

6.- DATA RECORDING

Diameter of the syringe ..............................

Value of the mass ....................................

Base area of the syringe ............................. (Show your work)

Pressure in the trapped air ......................... (Show your work)

TEMPERATURE

VOLUME

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