What is heat capacity?

Question

I want to know about heat capacity!!!

Answer 1

The amount of heat required to raise the material's temperate by a degree.

Temperature is just a measure of the speed of molecular movement inside a sample. At the theoretical limit of absolute zero all movement would be stopped, but that point can't be reached.

There are several different ways to use the term heat capacity; but each term is a measure of how much energy it takes to increase the temperature. You measure it with a thermometer and formulas or directly with a Calorimeter.

According to Wikipedia: http://en.wikipedia.org/wiki/Calorimeter
"A calorimeter is a device used for calorimetry, the science of measuring the heat of chemical reactions or physical changes as well as heat capacity. The word calorimeter is derived from the Latin word calor, meaning heat."

According to Wikipeida: http://en.wikipedia.org/wiki/Specific_heat_capacity
"Specific heat capacity, also known simply as specific heat, is the measure of the heat energy required to increase the temperature of a unit quantity of a substance by a certain temperature interval. The term originated primarily through the work of Scottish physicist Joseph Black who conducted various heat measurements and used the phrase “capacity for heat.”[1] More heat energy is required to increase the temperature of a substance with high specific heat capacity than one with low specific heat capacity. For instance, eight times the heat energy is required to increase the temperature of an ingot of magnesium as is required for a lead ingot of the same mass. The specific heat of virtually any substance can be measured, including chemical elements, compounds, alloys, solutions, and composites."

According to Wikipedia: http://en.wikipedia.org/wiki/Heat_capacity_ratio
"The heat capacity ratio or adiabatic index, is the ratio of the heat capacity at constant pressure (CP) to heat capacity at constant volume (CV). It is sometimes also known as the isentropic expansion factor and ratio of specific heats, and is denoted by γ (gamma) or κ (kappa). The latter symbol kappa is primarily used by chemical engineers."

According to Wikipedia: http://en.wikipedia.org/wiki/Volumetric_heat_capacity
"Volumetric heat capacity (VHC) describes the ability of a given volume of a substance to store internal energy while undergoing a given temperature change, but without undergoing a phase change. It is different from specific heat capacity in that the VHC depends on the volume of the material, while the specific heat is based on the mass of the material. If given a specific heat value of a substance, one can convert it to the VHC by multiplying the specific heat by the density of the substance."

According to Wikipeida: http://en.wikipedia.org/wiki/Heat_capacity_rate
"The heat capacity rate is heat transfer terminology used in thermodynamics and different forms of engineering denoting the ability of a fluid to resist change in temperature as heat transfer occurs. It is typically denoted as C, listed from empirical data experimentally determined in various reference works, and is typically stated as a comparison between a hot and a cold fluid, Ch and Cc either graphically, or as a linearized equation. It is an important quantity in heat exchanger technology common to either heating or cooling systems and needs, and the solution of many real world problems such as the design of disparate items as different as a microprocessor and an internal combustion engine."

Answer 2

Simply saying heat capacity is the amt of HEAT ABSORBED BY A SUBSTANCE.

mathematically,
Q = m* c * (t2-t1)
where c is heat capacity
Q is the heat absorbed.
t2 -t1 is heat difference.

To be more clear and scientific abt this concept.
HEAT CAPACITY AND SPECIFIC HEAT CAPACITY:
If we have to heat something up (without a phase change), for example 12 kg of copper from 20 °C to 80 °C, the amount of enthalpy we have to put in depends on three things. (1) The temperature difference to be achieved, in this case 60 K. (2) The mass, in this case 12 kg. (3) A property of the substance called specific heat capacity, which is a measure of how much energy is required to raise the temperature of 1 kg by 1 K. Copper has a specific heat capacity of 0.383 kilojoules per kilogram per kelvin (0.383 kJ kg-1 K-1). Therefore we have to put in 0.383 x 12 x 60 = 276 kJ.

If on the other hand, we had to heat up 12 kg of water from 20 °C to 80 °C, we would use the specific heat capacity of water, 4.184 kJ kg-1 K-1, and our calculation would be: 4.184 x 12 x 60 = 3012 kJ.

Note that these terms tend to be used loosely. What is properly the specific heat capacity is often referred to as the specific heat or the heat capacity. If in doubt, look at the units. Technically the heat capacity refers to the whole body, the specific heat capacity to a mass – in the SI system one kilogram. In thermodynamic tables, data is sometimes given per mole or kilomole instead of per kilogram, especially for gases. You may also come across older data in which the obsolete unit the calorie (= 4.184 J) is used and the mass is one gram. Sorry, but you will have to convert. Always look at the units.


A simple calculation
Suppose 15 kg of copper at 80 °C is put into a bath of 25 kg of water at 20 °C, and there are no heat losses to the surrounding. What will be the final condition?

Answer Both the copper and the water will have the same temperature, somewhere between 20 °C and 80 °C. The total enthalpy will be unchanged.

Let us take the reference condition as 20 °C. Thus the water has zero enthalpy, and the copper has 15 x (80-20) x 0.383 = 344.7 kJ. This is the enthalpy of the system.

Now the total heat capacity of the system is (mass x specific heat capacity of copper) + (mass x specific heat capacity of water) = (15 x 0.383) + (25 x 4.184) = 5.75 + 104.6 = 110.4 kJ K-1

In other words, it would take 110.4 kJ of enthalpy to raise the temperature of the whole system by 1 K (= 1°C).

Therefore adding 344.7 kJ of enthalpy would raise the temperature of the system by 344.7 ÷ 110.4 = 3.1 K, so the final temperature would be 23.1 °C.

Looking at this a different way, we can see that the specific heat capacity of water is 4.184 ÷ 0.383 = 10.92 times greater. Thus 15 kg of copper has the heat capacity of only 15 ÷ 10.92 = 1.37 kg of water. Thus adding this amount of water to 25 kg would dilute the 60 K temperature difference as 60 x 1.37 ÷ 26.37 = 3.1 K.

Answer 3

Specific heat capacity and heat capacity are different.Heat capacity or thermal capacity is the amount of heat energy required to raise the temperature of the whole body by 1 degree Celsius. If m is the mass of the body and C is the specific heat capacity, then:Q=mCT.As T=1degree Celsius, Q=mC×1=mc.
Therefore thermal capacity=Mass of the body×Specific heat.


Specific heat capacity,according to SI standards,of a substance is the amount of heat in joule(J) required to raise the temperature of 1 kg of the substance through 1 Kelvin.SI unit is J/kg ×K.

Answer 4

The heat capacity of a substance is the amount of heat required to change its temperature by one degree, and has units of energy per degree

Answer 5

There are two types of heat capacities, one is specific heat capacity, denoted as lower case c,c and the other one is molar heat capacity, denoted as upper case c, C.

The definition of specific heat capacity for a particular material is the heat required to increase the temperature of 1kg of the material by 1celcius.
Q = mc dT
where Q is heat
m is mass of the material
dT is the change of temperature of the material
c is the specific heat capacity of the material
So, c = Q/(m dT) ( unit is J/kg.celcius )

The definition of molar heat capacity for a particular material is the heat required to increase the temperature of 1 mol of the material by 1 celcius.
As we know, the relation between mol and mass is,
m = n M
where m is mass of the material
n is the mol of the material
M is the molar mass of the material.
From the equation above,
Q = m c dT
Q = n M c dT
Q = n C dT
C = Q/(n dT) ( unit si J/mol.celcius)
where C is the molar heat capacity
n is the mol of the material.

We can see that the relation between c and C is
C = M c
where M is the molar mass of the material.

If one object with higher heat capacity ( either specific or molar ), you will need more heat to rise the temperature of the object. For example, you will need to take more time to rise the temperature of water than to rise the temperature of alumium to a certain temperature with a constant heat source. This is because the heat capacity of water is higher than the heat capacity of aluminium.

Sry, if i wrote many unimportant things.

Answer 6

Each substance has unique spesific heat constant = c .

HEAT = M c (t2-t1),,,,,,M= mass of the sustance,,,,


HEAT = [heat capacity of this substance ] (t2-t1)
..
heat capacity = M c
.
.