Water specific heat capacity

For a given mass of substance, the substance with the smallest specific heat capacity (gold, 0.13 J/g °C) will undergo the largest increase in temperature. Conversely, the substance with the largest specific heat capacity (water, 4.184 J/g °C) will undergo the smallest increase in temperature. 

The dimensionless number Le is called the Lewis number (m Russian literature it is called the Luikov number). The Lewis number incorporates the specific heat capacity of humid air pCp (J/m C), the diffusion factor of water vapor in... 

Because the specific heat capacity of the water vapor is different from that of the dry air, the true dry-bulb mixed-stream air temperature can be determined only by means of a heat balance. 

The heat capacity of a subshince is defined as the quantity of heat required to raise tlie temperature of tliat substance by 1° the specific heat capacity is the heat capacity on a unit mass basis. The term specific heat is frequently used in place of specific heat capacity. This is not strictly correct because traditionally, specific heal luis been defined as tlie ratio of the heat capacity of a substance to the heat capacity of water. However, since the specific heat of water is approxinuitely 1 cal/g-°C or 1 Btiiyib-°F, the term specific heal luis come to imply heat capacity per unit mass. For gases, tlie addition of heat to cause tlie 1° tempcniture rise m iy be accomplished either at constant pressure or at constant volume. Since the mnounts of heat necessary are different for tlie two cases, subscripts are used to identify which heat capacity is being used - Cp for constant pressure or Cv for constant volume. Tliis distinction does not have to be made for liquids and solids since tliere is little difference between tlie two. Values of heat capacity arc available in the literature. ... 

Example 1.3 The specific enthalpy of water at 80°C, taken from 0°C hase, is 334.91 kj/kg. What is the average specific heat capacity through the range 0-80°C ... 

In salt brines, the water maybe considered as the heat transfer medium, since the specific heat capacity of the salt content is low (see Figure 12.3). The specific heat capacityofthe brine will therefore... 

Figure 12.4 Propylene glycol in water, (a) Eutectic curve, (b) Density and specific heat capacity...

Figure 5.1 is a graph of the specific heat capacity cp (heat capacity per gram) of aqueous sulfuric acid solutions at T — 298.15 K against A, the ratio of moles of water to moles of sulfuric acid. The values plotted were obtained from a very... 

In the SI system, the unit of heat is taken as the same as that of mechanical energy and is therefore the Joule. For water at 298 K (the datum used for many definitions), the specific heat capacity Cp is 4186.8 J/kg K. 

Prior to the now almost universal adoption of the SI system of units, the unit of heat was defined as the quantity of heat required to raise the temperature of unit mass of water by one degree. This heat quantity is designated the calorie in the cgs system and the kilocalorie in the mks system, and in both cases temperature is expressed in degrees Celsius (Centigrade). As the specific heat capacity is a function of temperature, it has been necessary to set a datum temperature which is chosen as 298 K or 25°C. 

In all of these systems, by definition, the specific heat capacity of water is unity. It may be noted that, by comparing the definitions used in the SI and the mks systems, the kilocalorie is equivalent to 4186.8 J/kg K. This quantity has often been referred to as the mechanical equivalent of heat J. 

A hydrocarbon oil of density 950 kg/m3 and specific heat capacity 2.5 kJ/kg K is cooled in a heat exchanger from 363 to 313 K by water flowing countercurrently. The temperature of the water rises from 293 to 323 K. If the flowrate of the hydrocarbon is 0.56 kg/s, what is the required flowrate of water ... 

Physical properties of water density 1000 kg/m3 viscosity 1 mN s/m2 thermal conductivity 0.6 W/m K specific heat capacity 4.2 kJ/kg K... 

Heat capacity is an extensive property the larger the sample, the more heat is required to raise its temperature by a given amount and so the greater is its heat capacity (Fig. 6.10). It is therefore common to report either the specific heat capacity (often called just specific heat ), Cs, which is the heat capacity divided by the mass of the sample (Cs = dm), or the molar heat capacity, Cm, the heat capacity divided by the amount (in moles) of the sample (Cm = C/n). For example, the specific heat capacity of liquid water at room temperature is 4.18 J-(°C) -g, or 4.18 J-K 1-g and its molar heat capacity is 75 J-K -mol1. 

These expressions may be rearranged to calculate the specific or molar heat capacity from the measured temperature rise caused by a known quantity of heat. The specific heat capacity of a dilute solution is normally taken to be the same as that of the pure solvent (which is commonly water). Table 6.2 lists the specific and molar heat capacities of sume common substances. 

KC1 (b) MgBr2 (c) KNO (d) NaOH is dissolved in 100. g of water. Assume that the specific heat capacity of the solution is... 

Steady-State Heat Exchanger Constant U=1.5 Heat transfer coefficient [kJ/s m2 K] Constant CP=4.18 Specific heat capacity [kJ/kg K] Constant WH=8.5 Mass flow rate of hot fluid [kg/s] Constant WC=4.17 Mass flow rate,cold fluid [kg/s] Constant TCIN = 323 Inlet cold water temp.[K] Constant TCOUT = 343 Outlet cold water temp. [K]... 

What is unique about these three properties of water boiling point, specific heat capacity, and density change over phase change ... 

The following is a partial list of the properties of water. Classify the properties as chemical or physical acts as a universal solvent, has high boiling point, exhibits high specific heat capacity, has density of about lg/mL, has a pH that is neutral, has no odor, is colorless. 

Calculate the specific enthalpy of water at a pressure of 1 bar and temperature of 200 °C. Check your value using steam tables. The specific heat capacity of water can be calculated from the equation ... 

The high thermal conductivity, the high specific heat capacity, and the high evaporation enthalpy of water make it suitable as solvent and heat removing fluid... 

Distilled water is produced from sea water by evaporation in a single-effect evaporator working on the vapour compression system. The vapour produced is compressed by a mechanical compressor of 50 per cent efficiency, and then returned to the calandria of the evaporator. Extra steam, dry and saturated at 650 kN/m2, is bled into the steam space through a throttling valve. The distilled water is withdrawn as condensate from the steam space. 50 per cent of the sea water is evaporated in the plant. The energy supplied in addition to that necessary to compress the vapour may be assumed to appear as superheat in the vapour. Calculate the quantity of extra steam required in kg/s. The production rate of distillate is 0.125 kg/s, the pressure in the vapour space is 101.3 kN/m2, the temperature difference from steam to liquor is 8 deg K, the boiling-point rise of sea water is 1.1 deg K and the specific heat capacity of sea water is 4.18 kJ/kgK. 

A solution of 500 kg of Na2S04 in 2500 kg water is cooled from 333 K to 283 K in an agitated mild steel vessel of mass 750 kg. At 283 K, the solubility of the anhydrous salt is 8.9 kg/100 kg water and the stable crystalline phase is Na2SO4.10H2O. At 291 K, the heat of solution is —78.5 MJ/kmol and the specific heat capacities of the solution and mild steel are 3.6 and 0.5 kJ/kg deg K respectively. If, during cooling, 2 per cent of the water initially present is lost by evaporation, estimate the heat which must be removed. 

Assuming that radiation losses amount to 20 kJ/kg of dry air used, determine the mass flow of dry air supplied to the dryer and the humidity of the outlet air. The latent heat of water vapour at 295 K = 2449 kJ/kg, the specific heat capacity of dried material = 0.88 kJ/kg K, the specific heat capacity of dry air = 1.00 kJ/kg K, and the specific heat capacity of water vapour = 2.01 kJ/kg K. 

Analysing Equations (3.6) and (3.7) helps us remember how the SI unit of heat capacity Cy is J K-1. Chemists usually cite a heat capacity after dividing it by the amount of material, calling it the specific heat capacity, either in terms of J K-1 mol-1 or J K-1g-1. As an example, the heat capacity of water is 4.18 J K-1g-1, which means that the temperature of 1 g of water increases by 1 K for every 4.18 J of energy absorbed. 

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 specific heat capacity of water is necessary to solve many problems. However, when reading the problem, it is often not apparent that you must use this value. If the problem mentions water, its specific heat capacity will often be part of the solution to the problem. 

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