i keep trying to do these problems and i don't understand them. please help me!!
1. Gas stored in a tank at 273 K has a pressure of 388 kPa. The save limit for the pressure is 825 kPa. At what temperature will the gas reach this pressure?
A. 850 K
B. 925 K
C. 580 K
D. 273 K
2. At 10 degrees C, the gas in a cylinder has a volume of 0.250 L. The gas is allowed to expand to 0.285 L. What must the final temperature be fore the pressure to remain constant? (Hint: Convert from degrees Celsius to kelvins using the expression C +273 = K)
A. 273 K
B.283 K
C. 323 K
D. 383 K
3.A gas has a volume of 5.0 L at a pressure of 50 kPa. What is the volume when the pressure is increased to 125 kPa? The temperature does not change.
A. 5.0 L
B. 3.0 L
C. 4.0 L
D. 2.0 L
All of these problems can be solved with the perfect gas law relationship
P V/T = constant
For example, in #3, T is constant so P*V = constant. Therefore
P1*V1 = P2*V2, where
"1" and "2" refer to initial and final conditions.
50 kPA*5.0 L = 125 kPa * P2
P2 = (50/125)*5.0 = 2.0 L (answer D)
Try doing the others yourself to get familiar with this type of problem
3. A
#3 is D because the pressure is increased 2.5 times. So, you would divide 5.0 by 2.5 to get 2.0 L.
Sure, I can help you with these problems. Let's break them down one by one.
1. For the first problem, we need to find the temperature at which the gas will reach a pressure of 825 kPa. We are given the initial temperature, which is 273 K, and the initial pressure, which is 388 kPa.
To solve this problem, we can use the combined gas law equation:
(P1 * V1) / T1 = (P2 * V2) / T2
where P1 and P2 are the initial and final pressures, V1 and V2 are the initial and final volumes (which are not given in this problem), T1 is the initial temperature, and T2 is the final temperature that we need to find.
Since the volume is constant in this problem, we can simplify the equation as follows:
P1 / T1 = P2 / T2
Now we can substitute the values we know into the equation:
(388 kPa) / (273 K) = (825 kPa) / T2
To isolate T2, we can cross-multiply:
388 kPa * T2 = (825 kPa) * (273 K)
Simplifying this equation will give us:
T2 = (825 kPa * 273 K) / 388 kPa
Now you can calculate the value of T2 and determine the correct answer among the given options.
2. For the second problem, we want to find the final temperature at which the pressure remains constant. We are given the initial temperature, initial volume, and final volume.
To solve this problem, we need to use the combined gas law equation mentioned earlier. In this case, since the pressure remains constant, the equation becomes:
(V1 / T1) = (V2 / T2)
Now we can substitute the given values:
(0.250 L) / (10 °C + 273 K) = (0.285 L) / T2
Solving for T2, we can cross-multiply:
(0.250 L) * T2 = (0.285 L) * (10 °C + 273 K)
Simplifying this equation will give us:
T2 = [(0.285 L) * (10 °C + 273 K)] / (0.250 L)
Now you can calculate the value of T2 and select the correct answer option.
3. For the third problem, we are given the initial volume, initial pressure, and final pressure. We need to find the final volume when the pressure is increased to 125 kPa. It is also mentioned that the temperature does not change.
To solve this problem, we can use Boyle's Law, which states that the pressure and volume of a gas are inversely proportional at a constant temperature. The equation is:
P1 * V1 = P2 * V2
Now we can substitute the given values:
(50 kPa) * (5.0 L) = (125 kPa) * V2
Simplifying this equation will give us:
V2 = (50 kPa * 5.0 L) / 125 kPa
Now you can calculate the value of V2 and select the correct answer option.
Remember, understanding the concept and knowing the appropriate formulas is essential in solving these types of problems. Make sure to always double-check your calculations and units to ensure accurate results.