When dealing with pressure and volume the number of particles
and temperature are kept constant. The relationship is inverse. Which
means that when the volume increases, the pressure decreases. This was shown in
our first lab that we did.
Boyle's law (sometimes referred to as the Boyle–Mariotte law, or
Mariotte's law) is an experimental gas law which describes how the pressure of
a gas tends to decrease as the volume of a gas increases. A modern statement of
Boyle's law is:
The
absolute pressure exerted by a given mass of an ideal gas is inversely
proportional to the volume it occupies if the temperature and amount of gas
remain unchanged within a closed system.
Boyle’s
law is basically saying that if the amount of gas and the temperature is
unchanged then when the volume increases, the pressure will decrease. Basically,
when the volume of a gas shrinks, the gas particles have less space to move
around so they hit the sides of the container more often. The more often the
gas particles hit the side of the container, the higher the pressure. So as the
volume decreases, the pressure increases. This graph below shows the
relationship between volume and pressure.
In the
second lab, we were dealing with pressure and the number of particles. In this
lab the volume and temperature are kept constant. This was a direct
relationship. As the pressure increases so does the number of particles. The amount
of pressure relies on the amount of particles that are present in that given
space. So if there are more particles, there is a greater pressure and if there
less particles the volume is also less. This explains why pressure and number
of particles is a direct relationship because if one goes up the other goes up
and if one goes down the other goes down as well. The graph below shows what
the direct realtionship looks like.
In the
third lab we were dealing with pressure and temperature. When the speed of the
gas particles increases, the gas particles hit the walls more often. The more
frequently the gas aparticles hit the walls, the higher the pressure. So, as
temperature increases, the pressure also increases. If the gas cools, the
impacts are less frequent and the pressure goes down. The relationship is also
direct because if the pressure decreases the temperature also decreases and when
the pressure goes up the temperature will also go up. Therefore, these two
variables are directly related. The graph below shows this relationship.
When
you drink through a drinking straw, you are not just sucking the liquid up the
straw. When you suck all you are doing is removing the air in the straw, which
allows the atmospheric pressure to act on the surface of the liquid to push it
up the straw. As you put the straw into your mouth, you close your lips around
the straw which seals off the surroundings from the inside of your mouth. When
you increase the volume inside your mouth th pressure goes down. It goes down so
that the outside surroundings has a higher pressure than the pressure in your
mouth. This process forces the drink up the straw and into your mouth.
A thermometer is a device that measure the temperature of
things. The red colored line in the middle of the thermometer moves up and down
depending on the temperature. The thermometer measures temperatures in Fahrenheit,
Celsius and another scale called Kelvin. Fahrenheit is used mostly in the
United States, and most of the rest of the world uses Celsius. Kelvin is used
by scientists. When you look at a regular outside bulb thermometer, you'll see
a thin red or silver line that grows longer when it is hotter. The line goes
down in cold weather. This liquid is sometimes colored alcohol but can also be
a metallic liquid called mercury. Both mercury and alcohol grow bigger when
heated and smaller when cooled. Inside the glass tube of a thermometer, the
liquid has no place to go but up when the temperature is hot and down when the
temperature is cold.
Overall
summary:
When we
say that something has pressure the particles of that substance are colliding
with the inside wall of the container. If something has a higher pressure
it means that the particles are more compact and are moving faster.Therefore,
colliding with the wall more often and at a faster rate. Temperature is how
fast the particles are moving inside something. The faster the particles are
moving, the hotter the substance will be. So if the particles are moving more
slowly, it will be at a colder temperature. That is why friction helps get us
warmer. When we rub our hands together, the particles start moving faster and
ultimately start to make us warmer.The only time that particles are not moving
is at zero degrees Kelvin. This shows that it has no kinetic energy. This is
also known as absolute zero. When there is a smaller volume, there is going to
be a greater pressure. Since there is still the same amount of particles, they
now have less space to occupy so they are more compact. Causing a greater
pressure in a smaller volume verses a greater volume.
