Answer:
Moles Lost = 0.0335 moles
Explanation:
This type of question requires the Ideal Gas Law equation. The equation looks like this:
PV = nRT
In this formula,
-----> P = pressure (kPa)
-----> V = volume (L)
-----> n = number of moles
-----> R = constant (8.314 L*kPa/mol*K)
-----> T = temperature (K)
(Step 1)
To find how many moles were lost, you first need to find how many moles you had to begin with. This can be done by plugging the starting values into the equation and solving for "n". But first, you need to convert Celsius to Kelvin (by adding 273.15).
P = 225 kPa R = 8.314 L*kPa/mol*K
V = 2.75 L T = 25°C + 273.15 = 298.15 K
n = ?
PV = nRT
(225 kPa)(2.75 L) = n(8.314 L*kPa/mol*K)(298.15 K)
618.75 = n(2478.8191)
0.250 = n
(Step 2)
Next, you need to find the number of moles in the container after it has been re-sealed. The volume is the same because the container did not change. The process should be the same as above.
P = 185 kPa R = 8.314 L*kPa/mol*K
V = 2.75 L T = 10°C + 273.15 = 283.15 K
n = ?
PV = nRT
(185 kPa)(2.75 L) = n(8.314 L*kPa/mol*K)(283.15 K)
508.75 = n(2354.1091)
0.216 = n
(Step 3)
Finally, you can find the number of moles lost by subtracting the final amount of moles from the original amount. When doing this calculation, I used the value of the moles saved in my calculator (with more decimal places) to get a more accurate number.
Moles Lost = Initial Moles - Final Moles
Moles Lost = 0.250 moles - 0.216 moles
Moles Lost = 0.0335 moles
