Specific heat capacity The

The specific heat capacity commonly has units of J/g-K. The specific heat capacity of water is 4.18 J/g-K. If we have the specific heat capacity, the mass, and the change of temperature, it is possible to determine the amount of energy absorbed or released (q). 

The view that the clay surface perturbs water molecules at distances well in excess of 10 A has been largely based on measurements of thermodynamic properties of the adsorbed water as a function of the water content of the clay-water mixture. There is an extensive literature on this subject which has been summarized by Low (6.). The properties examined are, among others, the apparent specific heat capacity, the partial specific volume, and the apparent specific expansibility (6.). These measurements were made on samples prepared by mixing predetermined amounts of water and smectite to achieve the desired number of adsorbed water layers. The number of water layers adsorbed on the clay is derived from the amount of water added to the clay and the surface area of the clay. 

Specific Heat Capacity the amount of heat required to raise the temperature of an object by 1 degree Celsius Spectator Ions ions that do not take part in a chemical reaction... 

Specific heat capacity The energy required to raise the temperature of one gram of a substance by one degree Celsius. 

SPECIFIC HEAT. Sometimes called specific heat capacity. The quantity of heat required to raise the temperature of unit mass of a substance by one degree of temperature. The units commonly used for its expression are die unit mass of one gram, the unit quantity of heat in terms of the calorie. See also Heat. 

Even if this equation implicitly assumes a zero-order reaction, it was initially developed for zero-order kinetics, and may also be used for other reaction kinetics, giving a conservative approximation since the concentration depletion that would slow down the reaction is ignored (see Section 2.4.3). It gives realistic values for strongly exothermal reactions, as decomposition reactions often are. The calculation of TMRad, according to Equation 11.2, requires the specific heat capacity, the specific heat release rate (q 0) at the runaway initial temperature T0, and the activation energy. 

Thermochemical measurements are based on the relationships between heat and temperature. The measurement that relates to the two is heat capacity, defined as the amount of heat that is required to raise the temperature of a substance 1°C. (The amount of substance is sometimes expressed in moles or in grams.) The heat capacity of a mole of a substance is known as the molar heat capacity, while the heat capacity for gram values of a substance are known as specific heat capacities. The specific heat of a substance is the amount of heat required to raise 1 gram of the substance 1°C. The formula that is used to calculate specific heat is Equation 17.4 ... 

A substance with a large specific heat capacity can absorb and release more energy than a substance with a smaller specific heat capacity. The symbol that is used for specific heat capacity is a lower-case c. The units are J/g-°C. 

Despite a wide range of specific heat capacities, the diatomic gases have molar heat capacities of about 29 J/moF°C, and the molar heat capacities of all the metallic elements are close to 26 J/moF°C. The latter generalization is known as the law of Dulong and Petit. 

The parameters for the density polynomial were obtained from available corresponding densities. Knowing the calibration constant for each set of experiments and the densities of the measured fluids allowed the calculation of c, and finally the specific heat capacity. The performances of the calorimetric arrangement have been tested by measuring the heat capacity for liquid n-hexadecane as well as of NaCl (aquous) in the molality range 0.1-2.0 mol kg". Measurements taken at different temperatures and pressures compare well with the literature data.. ... 

If both the substances have the same specific heat capacities, the term for mass transfer drops out of the equation. However in all other cases it does not assume a negligible value. In particular for substances such as water vapour and air, the specific heat capacities are so different that the mass transfer term cannot be removed. In addition it should be recognised that the energy equation agrees with that for pure substances when the specific heat capacities of the two components are equal and when no chemical reactions occur. 

Chemical reactions will not play any role in this discussion. The considerations here will be restricted to pure substances or binary mixtures which have components of approximately the same specific heat capacity. The energy equation (3.119) then agrees with that for pure substances (3.117). After introduction of the dimensionless quantities the continuity equation is... 

The thermal conductivity of a material is defined in terms of the transport of heat under steady-state conditions. On the other hand, one is often interested in the transport of heat when a specimen is not at equilibrium so that the flow of heat is transient. The thermal diffusivity a , which is defined by Equation 14.2, describes these time-dependent, non-steady-state aspects of heat flow. The thermal diffusivity is used to calculate the temperature (T) as a function of the position within the specimen (z) and the time (t) under non-steady-state conditions. It is related by Equation 14.3 to the thermal conductivity, the density, and the specific heat capacity. The values of X and a can be measured independently. However, often one of them (usually a) is estimated from the measured value of the other one (usually X) by using Equation 14.3. If X is in J/(K m sec), cp is in J/(g K) and p is in g/cc, then the a value calculated by using Equation 14.3 must be multiplied by 100 to convert it into our preferred diffusion units of cm2/sec. 

Note that in Example 10.3, to calculate the energy (heat) required, we took the product of the specific heat capacity, the sample size in grams, and the change in temperature in Celsius degrees. 

On the other hand, the calibration presumes a constant value for the product of coolant mass flow and specific heat capacity. The purpose of the calibration this time is twofold. For one, the proportionality of the difference in temperature between coolant inlet and outlet and the power input shall be calibrated. This way, rh, Cp,- becomes a calibration constant. Practice has shown, however, that this procedure allows an evaluation of the power output of the investigated process only to a limited extent of validity. It is much more recommendable to install a precision mass flowmeter in the coolant circuit, which allows the continuous registration of the measured signal... 

Specific Heat Capacity - The quantity of heat required to change the temperature of one unit weight of a material by one degree. 

Experimental investigations have shown that the thermal conductivity remains almost constant [8] or increases from the ambient temperature to resin decomposition [9, 10]. Consequently, similar to the specific heat capacity, the thermal conductivity before decomposition has been modeled as a constant value [7, 11]... 

For the effective specific heat capacity, the energy change during decomposition (i.e., decomposition heat) must be considered. The rate of energy absorbed for decomposition (endothermic reaction) is determined by the reaction rate, that is, the decomposition rate that is obtained by the decomposition model (Eq. (2.19)). Combining Eq. (2.19) and Eq. (4.30) gives ... 

The same trend is observed for the specific heat capacity. The intensity of the change in specific heat capacity (A is associated with T. Specific heat capacity of control PU is 1392 J/kg-K. Specific heat capacity of the PU composite increased by 5.8 % when 2% FR is added. However, specific heat capacity of FR-filled PU composites decreased by 3.5% and 14% when 4% and 6% FR respectively are added. A significant drop in specific heat capacity (A C ) is observed when more flame retardant is introduced to PU composites, therefore gradual and Unear reduction ocoured according to addition of FR (Sarier Onder 2007). 

If one can keep the number of moles and the volume constant, terms 2 and 3 are zero because dV and dn are zero. The change in heat, dQ, is then expressed by the first term alone. These conditions of zero dV and dn are used so often that (8U/3T)v, has been given a new name, the heat capacity (heat capacity at constant volume and constant number of moles). Speaking somewhat more loosely, one can say that the heat capacity is the amount of heat, necessary to raise the temperature of the system by one kelvin at constant volume. The heat capacity that refers to one gram of the substance is the specific heat capacity. The older term specific heat is to be abandoned since it would refer to the integral quantity U. This is the type of error in nomenclature that led, for example, to the questionable interpretation of Count Rumford s experiment in Sect. 2.1.1. 

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