May 8th
UPSC Science and Technology class:
We had our
6th Science and Technology class today.
The class
started with the physics concept Heating. Generally anything can be heated by
three methods :
Conduction
:
Conduction is the transfer of thermal energy through
direct contact. Heat transfer
in solids.
E.g.,
Heating of an Iron rod.
Convection:
Convection is the transfer of thermal energy through
the movement of a liquid or gas. Heat transfer in fluids. Transfer of heat from liquid to gas, liquid to liquid
and gas to gas.
E.g., The
property of Water:
If we take
water in a container, and heat a single molecule in it, it releases heat until
all molecules are equally heated by the circulation of the water molecules.
After all molecules are equally heated it goes for evaporation.
Radiation:
Radiation is the transfer of thermal energy through thermal
emission. Heat Transfer
through no medium.
E.g., The
sunlight takes approximately 8.5s to reach Earth from Sun. It travels through
vacuum (i.e.) no medium.
General
Standards:
Gas – Air
Liquid –
Water
Relative
properties of any liquid are compared only to water.
Relative
properties of any gas are compared only to air.
E.g., Gas
leaks: If the released gas is of higher
density than air it gets settled in the
ground. If the released gas is of lesser density than air it gets
evaporated into the atmosphere. E.g., Bhopal Gas leak.
Water:
Formula:
H2O
Water can
exist in three states :
Solid – Ice
Liquid –
Water
Gas – Water
Vapor
Phase
changes:
Change of
state from solid to liquid – melting
Change of
state from liquid to gas- boiling / Evaporation
Boiling- can take place only at
boiling point.
Evaporation – can take place at
any temperature.
Change of
state from gas to liquid – condensation
Change of
state from Liquid to solid – Freezing
Change of
state from Solid to gas or gas to solid – sublimation. E.g., Camphor,
Naphthalene balls
Specific
Heat capacity:
Specific heat capacity is defined as the amount
of heat required to raise the temperature of 1 kilogram of a
substance by 1 kelvin (SI unit of specific heat capacity J kg−1 K−1).
The heating which does not change the phase of the
substance.
E.g., Specific heat capacity of Water – 44184 J⋅kg−1⋅K−1
Specific Heat Capacity of Mercury - 0.1395 J⋅kg−1⋅K−1
CHEMISTRY
Substances:
Pure
substance – Pure substances are substances that are made up of only one
kind of particles and has a fixed or constant structure.
Mixture:
Homogeneous
mixture: A homogeneous mixture is a mixture in which the composition is uniform
throughout the mixture.
A
heterogeneous mixture is a mixture in which the composition is not uniform
throughout the mixture. A heterogeneous mixture consists of two or more phases.
Alloys:
Alloys are
metallic compounds made up of one metal and one or more metal or non-metal
elements.
Their
properties are different from that of their constituent elements.
Solution –
solvent + solute
An
unsaturated solution contains less than the maximum amount of solute.
A saturated
solution contains the maximum quantity of solute that dissolves at that
temperature. If it gets too saturated, crystals will form and drop out of
solution.
A
supersaturated solution is a solution that contains more than the maximum
amount of solute that is capable of being dissolved at a given temperature
Content Credits : Leo B Brindha
