Final answer:
Gay-Lussac's Law is used to determine that the pressure of a gas decreases proportionally to the decrease in temperature when the volume and amount of gas are constant. By applying this law, the student can calculate the expected pressure of hydrogen gas after a temperature drop.
Step-by-step explanation:
The question pertains to the effect of temperature changes on the pressure of a gas. Specifically, the student is asking for the expected pressure of hydrogen gas when the temperature decreases from 23 degrees C to 11 degrees C, assuming that the volume and the amount of gas (number of moles) remain constant.
To solve this, we can use Gay-Lussac's Law, which states that the pressure of a gas is directly proportional to its absolute temperature, provided that the volume is held constant. When we transform the temperatures from degrees Celsius to Kelvin by adding 273.15, we get the initial temperature (T1) of 296.15 K (23 + 273.15) and the final temperature (T2) of 284.15 K (11 + 273.15).
With the initial pressure (P1) given as 125 kPa, we can set up the equation P1/T1 = P2/T2, where P2 is the final pressure we want to find. By rearranging the equation to solve for P2, we get P2 = P1 × (T2/T1). Plugging in the known values, P2 = 125 kPa × (284.15/296.15), we can calculate the final pressure P2.