INTRO OF HEAT

 HEAT

In 18th and beginning of 19th century heat was considered was weight less fluid according to the caloric theory the hot body contains more caloric then the cold bodies.

Count Rumford Challenge on Caloric concept

In 1798 count Rumford (Benjamin) challenge the concept heat fluid. Count Rumford concluded that the heat is produced by friction while is caused by friction.

James   Joules Experiment On Heat

1840 James Joule support the theory of Count Rumford that:

Ø  Heat is not as the flow of substance (calorie).

Ø  Heat is the form of energy flow from hot body to cold body.

Ø  Heat is the form of energy that transfer body because of temperature’s difference.

Definition

“Heat is the sum of kinetic energy of all molecules or atoms of body system.”

Once the heat is transferred into body it will converted internal energy.

According to the kinetic theory of the molecule. The Molecules of the body always be in motion. The motion of the molecule is due to the kinetic energy which possessed by the molecule.

            Then the sum of the kinetic energy of all the molecules is called “Heat”.

INTERNAL ENERGY

                                All type of energies like K.E, P.E, Transnational, Rotational energy along with binding energies of nuclear energy called as internal of the heat also can be define as the energy evolved in care of combustion reaction, exothermic reaction, fission, fusion reaction but from high temperature to low temperature.

Differentiate between the heat and temperature

 Differentiate between the heat and temperature

 

Heat	Temperature
Heat is the form of energy us transit from one body to another due to temperature difference.	Temperature is the degree of hotness or coldness.
It is the total kinetic energy of the body.	It is the average kinetic energy of the body.
It’s unit is Joule	It’s units are oC, oF, and oK

Heat Capacity/Specific Heat Capacity and molar specific heat capacity

s

Heat Capacity

Heat capacity (C) of a substance is “the quantity of heat needed to raise the temperature of a substance by one degree Celsius (or one Kelvin).” The heat capacity differ from substance to substance. The amount of substance is directly proportional to the heat capacity. That means by doubling the mass of substance, heat capacity can be doubled.

 C = QΔ/Δt

Where the QΔ is the amount of heat required with the change or temperature .

 Unit:  The S.I unit of heat capacity is JK^-1.

 

Specific Heat Capacity

It can be defined as “the quantity of heat required to raise the temperature of one gram of a substance by one degree Celsius (or one Kelvin) at a constant pressure.”

 Specific heat or specific heat capacity (s) is the heat capacity, which is independent of the amount of substances

            Thus if the ΔQ is the amount of heat added to raise the temperature of ‘m’ kg of a substance through ΔT, then

ΔQ  µ ΔT_________(a)

ΔQ  µ m_________(b)

Combine both (a) and (b)

ΔQ  µ m ΔT

   ΔQ = c m ΔT

     c = ΔQ/m ΔT

Where ‘c’ is the proportionality constant known as specific capacity of the substances.

Unit

The unit of specific heat is Jg^-1oC^-1.

Molar Specific Heat Capacity

Heat required to raise the one degree temperature of one mole of substances.

ΔQ = c m ΔT _______(1)

n = molar mass (m) / molecular mass (M)

n = m / M

m = Mn_______(a) 

                Put equation in (a) in (1)

ΔQ = c nMΔT

Where “Product of Molecular mass (M) and  specific heat capacity “c” is equal to Molar specific heat capacity ‘C”.

C = Mc

            Then the equation ‘2’ will be

                                                                            ΔQ = nC

                                                                        C = ΔQ / n ΔT