USING CALORIMETER AIM To study the relationship between the temperature of a hot body and time by plotting a cooling curve. APPARATUS REQUIRED Copper calorimeter with stirrer, one holed rubber cork, thermometer, stop clock, heater / burner, water, clamp and stand NEWTON’S LAW OF COOLING Newton’s law of cooling states that the rate of change of the temperature of an object is proportional to the difference between its own temperature and the ambient temperature. (i.e., the temperature of its surroundings) dT dt ∝ ( T − T ) where dT dt → Rate of change of temperature ( ° C) T → Temperature of water ( ° C) T → Room Temperature ( ° C) DIAGRAM EXPERIMENTAL SETUP OF NEWTON’S LAW OF COOLING PROCEDURE ¾ Note the room temperature as (T ) using the thermometer. ¾ Hot water about °C is poured into the calorimeter.
¾ Close the calorimeter with one holed rubber cork. ¾ Insert the thermometer into calorimeter through the hole in rubber cork. ¾ Start the stop clock and observe the time for every one degree fall of temperature from °C. UNIT- (XI- - ) PRACTICAL FIRST UNIT- (XI- - ) PRACTICAL FIRST - - - - Practical ¾ Take sufficient amount of reading, say closer to room temperature ¾ The observations are tabulated ¾ Draw a graph by taking time along the x axis and excess temperature along y axis.
MODEL GRAPH RELATION BETWEEN TIME AND TEMPERATURE EXCESS TEMPERATURE TIME O ROOM TEMPERATURE (T ) = °C OBSERVATIONS Measuring the change in temperature of water with time Time (s) Temperature of water (T) °C Excess temperature ( T – T ) °C RESULT The cooling curve is plotted and thus Newton’s law of cooling is verified. UNIT- (XI- - ) PRACTICAL FIRST UNIT- (XI- - ) PRACTICAL FIRST - - - - Practical