CALORIMETRY
Calorimetry is the science or act of measuring changes in state variables of a body for the purpose of deriving the heat transfer associated with changes of its state due for example to chemical reactions, physical changes, or phase transitions under specified constraints. Calorimetry is performed with a calorimeter.
CALORIMETER
A calorimeter is an object used for calorimetry, or the process of measuring the heat of chemical reactions or physical changes as well as heat capacity.
A calorimeter is an experimental device in which a chemical reaction or physical process takes place. The calorimeter is well-insulated so that, ideally, no heat enters or leaves the calorimeter from the surroundings. For this reason, any heat liberated by the reaction or process being studied must be picked up by the calorimeter and other substances in the calorimeter.
FIRST LAW OF THERMODYNAMICS
The change in a system's internal energy is equal to the difference between heat added to the system from its surroundings and work done by the system on its surroundings.
LATENT HEAT
The quantity of heat absorbed or released by a substance undergoing a change of state, such as ice changing to water or water to steam, at constant temperature and pressure. Also called heat of transformation. [Heat absorbed or radiated during a change of phase at constant temperature and pressure]
SENSIBLE HEAT
Sensible heat is heat exchanged by a body or thermodynamic system that has as its sole effect a change of temperature.
MELTING POINT
The temperature at which a solid becomes a liquid. For a given substance, the melting point of its solid form is the same as the freezing point of its liquid form. The melting point of ice is 32°F (0°C); that of iron is 2,797°F (1,535°C).
FREEZING POINT
The temperature at which a liquid becomes a solid. For a given substance, the freezing point of its liquid form is the same as the melting point of its solid form. The freezing point of water is 32°F (0°C); that of liquid nitrogen is -345.75°F (-209.89°C).
STANDARD PRESSURE
A pressure at which standardized measurements may be made, equal to 105 pascals or 1 atmosphere. [the pressure that will support a column of mercury 760 mm high at sea level and 0 degrees centigrade]
STANDARD TEMPERATURE
A condition for standardized measurements, usually equal to either 273 K (0°C) for properties of gases or 298 K (25°C) for thermodynamic measurements. [Exactly zero degrees centigrade]
SMELT (V) - Extract (metals) by heating; (Metallurgy) (tr) to extract (a metal) from (an ore) by heating
PROBLEM – 01
In a furnace 150 kg of tin is to be melted in one hour. What should be the rating of the furnace if smelting temperature (melting temperature) of tin = 23.5 degree centigrade,
Specific heat capacity of tin = 0.05, latent heat of tin = 13.3 kcal/kg and initial temperature of tin is 35 degree centigrade.
PROBLEM – 02
A low frequency induction furnace has a secondary voltage of 15 V and takes 600 kW at 0.6 power factor when the hearth is full. If the secondary voltage is maintained at 15 V, determine the power absorbed and the power factor when the hearth is half full. Assume the resistance of the secondary circuit to be thereby doubled and the reactance to remain the same.
PROBLEM – 03
Determine the efficiency of a high frequency induction furnace which takes 10 minutes to melt 2 kg of aluminium, the input current to the furnace being 5 kW and initial temperature 15 degree centigrade.
Specific heat of aluminum = 0.212
Melting point = 660 degree centigrade
Calorimetry is the science or act of measuring changes in state variables of a body for the purpose of deriving the heat transfer associated with changes of its state due for example to chemical reactions, physical changes, or phase transitions under specified constraints. Calorimetry is performed with a calorimeter.
CALORIMETER
A calorimeter is an object used for calorimetry, or the process of measuring the heat of chemical reactions or physical changes as well as heat capacity.
A calorimeter is an experimental device in which a chemical reaction or physical process takes place. The calorimeter is well-insulated so that, ideally, no heat enters or leaves the calorimeter from the surroundings. For this reason, any heat liberated by the reaction or process being studied must be picked up by the calorimeter and other substances in the calorimeter.
FIRST LAW OF THERMODYNAMICS
The change in a system's internal energy is equal to the difference between heat added to the system from its surroundings and work done by the system on its surroundings.
LATENT HEAT
The quantity of heat absorbed or released by a substance undergoing a change of state, such as ice changing to water or water to steam, at constant temperature and pressure. Also called heat of transformation. [Heat absorbed or radiated during a change of phase at constant temperature and pressure]
SENSIBLE HEAT
Sensible heat is heat exchanged by a body or thermodynamic system that has as its sole effect a change of temperature.
MELTING POINT
The temperature at which a solid becomes a liquid. For a given substance, the melting point of its solid form is the same as the freezing point of its liquid form. The melting point of ice is 32°F (0°C); that of iron is 2,797°F (1,535°C).
FREEZING POINT
The temperature at which a liquid becomes a solid. For a given substance, the freezing point of its liquid form is the same as the melting point of its solid form. The freezing point of water is 32°F (0°C); that of liquid nitrogen is -345.75°F (-209.89°C).
STANDARD PRESSURE
A pressure at which standardized measurements may be made, equal to 105 pascals or 1 atmosphere. [the pressure that will support a column of mercury 760 mm high at sea level and 0 degrees centigrade]
STANDARD TEMPERATURE
A condition for standardized measurements, usually equal to either 273 K (0°C) for properties of gases or 298 K (25°C) for thermodynamic measurements. [Exactly zero degrees centigrade]
SMELT (V) - Extract (metals) by heating; (Metallurgy) (tr) to extract (a metal) from (an ore) by heating
PROBLEM – 01
In a furnace 150 kg of tin is to be melted in one hour. What should be the rating of the furnace if smelting temperature (melting temperature) of tin = 23.5 degree centigrade,
Specific heat capacity of tin = 0.05, latent heat of tin = 13.3 kcal/kg and initial temperature of tin is 35 degree centigrade.
PROBLEM – 02
A low frequency induction furnace has a secondary voltage of 15 V and takes 600 kW at 0.6 power factor when the hearth is full. If the secondary voltage is maintained at 15 V, determine the power absorbed and the power factor when the hearth is half full. Assume the resistance of the secondary circuit to be thereby doubled and the reactance to remain the same.
PROBLEM – 03
Determine the efficiency of a high frequency induction furnace which takes 10 minutes to melt 2 kg of aluminium, the input current to the furnace being 5 kW and initial temperature 15 degree centigrade.
Specific heat of aluminum = 0.212
Melting point = 660 degree centigrade
Latent heat of fusion of aluminum = 76.8 kCal/kg.
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