SCIENCE 3RD QUARTER EXAM Flashcards
Gases
Gases are important factors in sustaining life here on
earth.
● What gas is very important to us humans? Why?
● For animals and humans, oxygen is very important
because both organisms utilize it where different
biological processes are involved, such as cellular
respiration.
The characteristics of gases are described
fully in terms of four parameters
Volume
Pressure
Temperature
Number of moles
. Volume
● Volume of a solid object is the amount
of space occupied by the object.
● It is a derived unit, because it is a
result from other measurements.
(V = l x w x h)
. Volume
The volume of gas is measured in terms of the following
SI units and conversion:
● Basic SI Unit: m3
(cubic meter)
● Derived Unit: Liter (L)
1 L = 0.001 m3
1 cm3 = 0.001 L
1 mL = 1 cm3
Pressure
● It is defined as the force applied per unit area.
● It also refers to the behavior of fluids such as liquids &
gases rather than the word force
-Solid
-liquid
-gas
Temperature
● Refers to the hotness or coldness of an object.
● It is also defined as the measure of the average
kinetic energy of the particles in an object.
● The faster the particles are moving, the more kinetic
energy they have.
● When we measure the temperature of an object,
we’re actually getting the average kinetic energy
Kinetic Molecular
Theory
● Gas laws were born through observation and
description of the behavior of gases in microscopic
perspective, and through the properties of gases that
can be directly observed by the person.
● These gas laws were formulated by several scientists
such as Robert Boyle, Jacques Charles, and Joseph Louis
Gay-Lussac.
Atomic Theory
All substances are made
up of a large number of
small particles.
Kinetic Molecular
Theory
The pressure of gas results
from the collisions of the gas
Kinetic Molecules theory
Theory
The pressure of gas results
from the collisions of the gas
particles with other gas
particles
Number of moles
• 1 mole = 6.02 x 1023 (Avogadro’s constant)
• Unlike temperature, the mole depends on the
number of particles.
• The higher the number of moles means the
higher amount of substance.
The Kinetic Molecular Theory states that
- Gases consist of tiny particles. ;
- These particles are so small, compared with the distance
between them, that the volume of the individual particles
can be assumed to be negligible. ; - The particles are in constant random motion colliding with
the wall of the container. These collisions with the walls
cause the pressure exerted by the gas. ; - The particles do not attract nor repel each other; and
- The average kinetic energy of gas particles is directly
proportional to the temperature of the gas.
Boyle’s Law
● Robert Boyle (1627 – 1691) was an
Irish-born gentleman philosopher who
did research and investigation in
physics, chemistry, alchemy, and
theology.
● He studied the behavior of gases.
● He expanded on the assumption of
Rene Descartes, who said that
pressure is due to the restless
agitation of the air particles.
Boye’s law
● Boyle proved his law for both great
and small pressures using the nowfamous J-tube experiment
Mercury J-Tube Experiment
● Using a J-shaped piece of glass tubing that was sealed on
one end that Boyle employed, he was able to establish the
relationship between volume and pressure.
● Varying amounts if mercury were added to the J-shaped
tube with gas trapped in the sealed end of the tube and
were used to vary the pressure of the system.
● He systematically varied the pressure and measured the
volume of gas.
● These measurements were performed using a fixed amount
of gas and a constant temperature.
Mercury J-Tube Experiment
● Boyle noticed that when temperature is held constant, the
Volume (V) of a given amount of gas decreases as the pressure
(P) is increased.
● His experiment proved that pressure is inversely proportional to
the volume of gas at constant temperature; that is the volume
decreases with increasing pressure and vice-versa.
