Final Chemistry Notebook

127
3. The pressure of nitrogen gas in a light bulb is 60 kPa at 25°C. Calculate the pressure of the gas
when the temperature inside the bulb rises to 167°C after the bulb is lighted up?
60/25=p/167
+273 +273
60/298=p/440
Combined gas law
298=269400
p=88.590604013
p=90
90 Kpa
The combined gas law makes use of the relationships shared by pressure, volume, and temperature:
the variables found in other gas laws, such as Boyle's law, Charles' law and Gay-Lussac's law. Let's
review the basic principles of these three laws.
Imagine you are a diver, and you begin your dive with lungs full of air. As
you go deeper under water, the pressure you experience in your lungs
increases. When this happens, the air inside your lungs gets squished, so
the volume decreases. This is an example of Boyle's law in action, which
states that the higher the pressure (P), the lower the volume (V), as
shown in this image. Here, k is any constant number.
Have you ever tried putting a balloon in the refrigerator and notice that it
shrinks? As the temperature of the refrigerated balloon decreases, the
volume of the gas inside the balloon also decreases. When you take the
balloon out of the refrigerator, it reverts to its original size, so the opposite is
also true; when the temperature increases, the volume also increases. The
shrinking balloon serves as a demonstration of Charles' law, which states
that the higher the temperature (T), the higher the volume (V).
Imagine yourself driving down a road, which can cause the
temperature to increase within your tires. As a result, the air inside the
tires expands, and the pressure increases. This is an example of Gay-
Lussac's law, which shows the relationship between pressure (P) and
temperature (T) when the volume remains constant; as the
temperature increases, the pressure also increases.
When we put Boyle's law, Charles' law, and Gay-Lussac's law together, we come up with the
combined gas law, which shows that:
Pressure is inversely proportional to volume, or higher volume equals lower pressure.
Pressure is directly proportional to temperature, or higher temperature equals higher pressure.
Volume is directly proportional to temperature, or higher temperature equals higher volume.
Let's take a look at the formula for the combined gas law. Here, PV / T = k shows how pressure,
volume and temperature relate to each other, where k is a constant number.
The formula for the combined gas law can be adjusted to compare two sets of conditions in one
substance. In the equation, the figures for pressure (P), volume (V), and temperature (T) with
subscripts of one represent the initial condition, and those with the subscripts of two represent the
final condition.