Temperature | Chemistry for EmSAT Achieve PDF Download

Definition

Temperature signifies the degree of hotness or coldness of an object. Specifically, it quantifies the kinetic energy of particles within the object. Higher kinetic energy corresponds to higher temperature, and vice versa. Temperature plays a crucial role across various domains, impacting everyday life and scientific fields from physics to geology.

Relationship between Temperature and Kinetic Energy

Temperature is intimately linked with the kinetic energy of particles. According to the kinetic-molecular theory, the temperature of a substance correlates with the average kinetic energy of its particles. Heating a substance increases the motion of its particles, raising the average kinetic energy and thus the temperature. Different states of matter—solid, liquid, and gas—exhibit varying degrees of kinetic energy, influencing their temperature behavior.

Differentiating Heat and Temperature

Heat and temperature are distinct concepts. Heat refers to the transfer of thermal energy between molecules within a system, measured in joules, while temperature denotes the average kinetic energy of molecules within a material or system, measured in Celsius (°C), Kelvin (K), or Fahrenheit (°F). Heat represents energy transfer, while temperature quantifies the intensity of molecular motion.

Methods of Temperature Measurement

Temperature measurement relies on indirect methods due to the minuscule size of molecules. Thermometers, utilizing the principle of thermal expansion, are commonly employed for temperature measurement. Liquid thermometers, for instance, gauge temperature changes by observing the expansion of a liquid like mercury. Other temperature sensors, such as RTDs and thermocouples, are utilized for specific applications.

Temperature Scales

Temperature is measured using standardized scales, including Celsius, Fahrenheit, and Kelvin. Each scale has defined reference points: Celsius scale sets the freezing and boiling points of water at 0°C and 100°C respectively, Fahrenheit scale sets them at 32°F and 212°F, while Kelvin scale sets absolute zero at 0 K. Kelvin scale, being absolute, is widely used in scientific endeavors.

Thermal Equilibrium

Thermometers function on the principle of thermal equilibrium, where two systems in thermal contact eventually reach the same temperature. At thermal equilibrium, heat transfer ceases, and both systems stabilize. This principle underpins accurate temperature measurement.

Effects of Temperature

Temperature variations induce diverse effects on physical and chemical processes. These effects include alterations in solubility, density, vapor pressure, and electrical conductivity of materials, as well as influencing chemical reaction rates and thermal radiation properties.