CH 10: Thermal Properties of Matter

• All metals have internal energy which is responsible for the temperature and state of the method.
• Total molecular potential energy is related to the internal and intermolecular forces and the distance between molecules.
• Molecules with more potential energy are further apart from one another.
• Water molecular kinetic energy is due to the vibration of the molecules and is related directly to the temperature of an object.
• The higher the temperature of an object, the greater its total molecular kinetic energy.
• Internal energy has potential energy and kinetic energy.
• Potential energy is responsible for the states of the method which are solid, liquid, or gas.
• Kinetic energy is responsible for the temperature of the object.
• The heating curve of water starts at negative 20 degree celsius and increases until it reaches 0 degree celsius, transitioning from solid state (ice) to liquid state.
• The cooling curve of water starts at 120 degrees celsius and decreases until it reaches 100 degrees celsius, transitioning from gas state to liquid state.
• Kinetic energy decreases while potential energy is constant as the temperature decreases.
• The formula for specific heat capacity is: Capital C equals Q over the change of temperature delta theta or more commonly Q equals Capital C delta theta.
• Specific latent heat of vaporization is the amount of thermal energy needed to change the state of a substance from liquid to gas without changing its temperature.
• Specific latent heat of fusion is the amount of thermal energy needed to change the state of a substance from solid to liquid without changing its temperature.
• Specific heat capacity is the amount of thermal energy needed to raise the temperature of an object by one degree.
• A good thermal insulator will have high heat capacity or specific heat capacity.
• The amount of thermal energy in joules is represented as Q and the change in temperature in kelvin or degree celsius is represented as delta theta.
• The larger the amount of heat capacity or specific heat capacity, the more energy is needed to increase the temperature of the substance.
• Specific latent heat is the amount of thermal energy needed to change the state of a substance from solid to liquid without changing its temperature.
• A good thermal conductor will have low heat capacity or specific heat capacity.
• The heating curve of water can be summarized as follows: solid state (ice) to liquid state, with the temperature increasing as the kinetic energy increases and the potential energy constant.
• The cooling curve of water can be summarized as follows: gas state to liquid state, with the temperature decreasing as the kinetic energy decreases and the potential energy constant.
• Wind prevents the building up of a layer of vapor molecules at the surface of the liquid, increasing evaporation rate.
• Factors affecting the rate of evaporation include temperature, boiling point of a liquid, and surface area of the liquid.
• The formula for the change of state from liquid to gas is Lv = q over m, where Lv is the specific latter heat of vaporization in joules per kg, q is the amount of thermal energy in joules, and m is the mass of the substance in kg.
• Liquids with lower boiling point will evaporate faster, and a larger exposed surface area provides more space for molecules to escape, hence evaporation is faster.
• Evaporation is a slow process that happens at the surface of the liquid, while boiling is a quick process that happens throughout the liquid.
• Examples of evaporation include sweat evaporating on our skin, which draws away heat and cools us, and dogs salivating to cool themselves down.
• Boiling is a process that only happens at a fixed temperature, known as the boiling point.
• Evaporation is a process where molecules at the surface of the liquid gain enough energy to overcome intermolecular attractive forces and escape into surrounding.
• Air pressure exerts pressure on the surface of the liquid, slowing down evaporation rates.
• A substance undergoes boiling when it absorbs heat from a heat source, while a substance undergoes evaporation when it loses heat to the surrounding.
• When the surrounding air is humid, there is a high concentration of water vapor in the air, which slows down the evaporation rate.