Chemical Changes are accompanied by a change in energy. When energy is given off during the reaction, temperature of the surrounding increases. When energy is absorbed during the reaction, the temperature of the surrounding decreases.
02 Interpreting Temperature-Time Graph of Surroundings during Reaction
a) For Reaction involving absorption of energy into the system:
Energy is taken into the system when reaction is taking place. The thermometer recording the temperature recorded shows the temperature of surrounding temperature. Since energy is taken into the system, the surrounding temperature decreases. However, after the completion of reaction, temperature increases as heat is now released from the system for the system to reach thermal equilibrium with the surrounding. The room temperature is 25 degree Celsius.
Examples of Changes involving absorption of energy: Boiling, Melting, Sublimation, dissolving, decomposition etc...
b) For Reaction involving release of energy into the system:
Energy is released to the system when reaction is taking place. The thermometer recording the temperature recorded shows the temperature of surrounding temperature. Since energy is removed from the system, the surrounding temperature increases. However, after the completion of reaction, temperature decreases as heat is now taken into the system for the system to reach thermal equilibrium with the surrounding. The room temperature is 25 degree Celsius.
Examples of Changes involving release of energy: Combustion, photosynthesis, freezing, condensation etc...
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