Charles’ Law

Objectives

To observe the effect of temperature on gas volume

Introduction

Charles's law states that at constant temperature, the volume of a fixed mass of gas is directly proportional to its absolute temperature. The mathematical expression of Charles’ law is as follows

 v inversely proportional to t( T = 273 + t ºc)

Or

          

  Charles’ law can be represented graphically by plotting the volume of a given gas against temperature. On extrapolation, the graph cuts the temperature at -273 ºC. This temperature is called absolute zero and was adopted as the zero on the kelvin scale or the absolute temperature scale.

Equipment

·        # Watch

·         #Erlenmeyer Flask with stopper

·         #500 ml tube

·         #Rubber stopper and clip

·         #Tripod stand

·         #Thermometer

·         #Bunsen burner

Reagent

-Nil-

Procedure

1.    1. The erlermeyer flask was weighed with the rubber stopper and its clip.

2.    2. Erlenmeyer flask was placed in the beaker with water.

3.    3. The water was boiled at least for 10 minutes without stopper so that the air inside the flask will have same temperature with the water boiling point.

4.    4. Sink was filled with water.

5.    5. Finished heating the flask, the end of the rubber tube was clip and marked.

6.    6. The flask removed from the boiling water and then the end of the tube was soaked together with the clip. Flask was leave in open air.

7.    7. The flask was unclipped to allow the water to get in. The air inside the flask reach the water temperature. Then flask was soaked again in the sink.

8.    8. The tube was clipped again at respective mark and removed from the sink.

9.    The reading at the air pressure meter was noted down.

Result

a)    Flask mass + assembles = 124.44 g

b)    Flask mass + assembles + inhaled water = 125.74 g

c)    Flask mass + assembles + water(full flask) = 248.2 g

Data elaboration

a)    Full flask water mass = 248.2 g

b)    Inhaled water mass = 1.3 g

c)    Inhaled water volume = 1.3 g

d)    Air volume at 100°C

= full flask water volume

= (a) / water density

= 248.2 g

e)    Air volume at room temperature :

= flask air volume at 100°C – inhaled water volume

= (d) – (c)

= 246.9 g

Question

1.    At What temperature, the calibration line cut the temperature axis. Compare with the theoretical value.

In theory, the temperature cut the axis at -273°C and this is called absolute zero.

2.    By using the Charles’ law and gas volume at 100ºC from your experiment, calculate the theoretical volume at the water in the sink temperature

Charles’ law

248 g                    =          V2

(100 + 273) k              (29+273)K

Therefore, V2 = 200.7 g