Be careful to cross-multiply correctly when you see a set up like the one just above.
When the temperature is changed to standard, what is the new pressure?Ģ) Cross multiply and divide for the new pressure.
This is because the problem is asking about the relationship between pressure and temperature the volume (as well as the moles) remains constant.Įxample #2: 5.00 L of a gas is collected at 22.0 ☌ and 745.0 mmHg. Notice that the volume never enters the problem. Insert values into the equation to get:Ģ) The question asks for Celsius, so you subtract 273 to get the final answer of 38.3☌. What would be the required temperature (in Celsius) to change the pressure to standard pressure?ġ) Change 25.0 ☌ to 298.0 K and remember that standard pressure in kPa is 101.325. Make sure to convert any Celsius temperature to Kelvin before using it in your calculation.Įxample #1: 10.0 L of a gas is found to exert 97.0 kPa at 25.0 ☌. The second one, of course, resulting from cross-multiplication of the equation in fractional form. Besides which, the value of K would shift based on what pressure units (atm, mmHg, or kPa) you were using.īe aware that you can also see this equation written as: It is important to know the PT data pairs obey a constant relationship, but it is not important for us what the exact value of the constant is. That means a container with rigid walls.Īs with the other laws, the exact value of k is unimportant in our context. Keep in mind that when volume is not discussed (as in this law), it is constant. If the temperature is changed to a new value called T 2, then the pressure will change to P 2. Let P 1 and T 1 be a pressure-temperature pair of data at the start of an experiment. This means that the pressure-temperature fraction will always be the same value if the volume and amount remain constant. The mathematical form of Gay-Lussac's Law is: This means there are two connected values and when one (either P or T) goes up, the other (either P or T) also increases. Gay-Lussac's Law is a direct mathematical relationship. This means the gas pressure inside the container will decrease, since the container has rigid walls (volume stays constant). This means gas molecules will move slower and they will impact the container walls less often. This means the gas pressure inside the container will increase, since the container has rigid walls (volume stays constant).Ģ) Suppose the temperature is decreased. This means gas molecules will move faster and they will impact the container walls more often. KMT was developed in its modern form about 50 years later.ġ) Suppose the temperature is increased. What makes them true? We can make brief reference to the ideas of kinetic-molecular theory (KMT), which Gay-Lussac did not have access to in the early 1800's. In words:ġ) If the temperature of a container is increased, the pressure increases.Ģ) If the temperature of a container is decreased, the pressure decreases. Gay-Lussac's Law gives the relationship between pressure and temperature when volume and amount are held constant. Maybe I'll learn more of the details someday. That is pretty much all the ChemTeam knows. Discussion and Ten Examples Boyle's Law Combined Gas Law Gay-Lussac's Probs 1-10 Charles' Law Ideal Gas Law Return to KMT & Gas Laws Menu Avogadro's Law Dalton's Law Diver's Law Graham's Law No Name Lawĭiscovered by Joseph Louis Gay-Lussac in the early 1800's.