Calculate the pressure of 4.80g of ozone, O3, in a 2.45 L flask at 25 degrees C. Assume that the ozone completely decomposes to the molecular oxygen.
2O3(g) --> 3O2(g)
Calculate the pressure inside the flask once the reaction is complete.
mols O3 = g/molar mass = 4.8/48 = 0.1
Pressure before O3 decomposes is then
P = nRT/V = ?
After decomposition you have
2O3 ==> 3O2
0.1 mol O3 x (3 mols O2/2 mols O3) = ? and use P = nRT/V again to find the O2 pressure.
ok I set up the first one right, and got P=.998 atm
The after composition makes sense and I got P = 20.0 atm
Are these correct?
0.998 is ok. 20.0 is not.
0.1 mol x (3 mols O2/2 mols O3) = 0.1*1.5 = 0.15 and if you substitute 0.15 for n in the equation surely you don't get 20 atm. Wouldn't the correct answer logically be P2 = 1.5*P1 = 0.998*1.5 = about 1.5?
Thanks!
To calculate the pressure inside the flask once the reaction is complete, we need to use the ideal gas law equation:
PV = nRT
Where:
P = Pressure
V = Volume
n = Number of moles
R = Ideal gas constant
T = Temperature (in Kelvin)
To solve this problem, we need to follow the following steps:
Step 1: Convert the temperature from Celsius to Kelvin.
The temperature given is 25 degrees Celsius. To convert it to Kelvin, we use the formula:
T(K) = T(C) + 273.15
So, the temperature in Kelvin is:
T(K) = 25 + 273.15 = 298.15 K
Step 2: Calculate the number of moles of ozone, O3.
To calculate the number of moles, we need to use the molar mass of ozone, which is 48.0 g/mol.
Given mass of ozone = 4.80 g
Number of moles of ozone = (Given mass of ozone) / (Molar mass of ozone)
Number of moles of ozone = 4.80 g / 48.0 g/mol
Number of moles of ozone = 0.10 mol
Step 3: Calculate the number of moles of molecular oxygen, O2.
According to the balanced chemical equation, 2 moles of ozone decompose to form 3 moles of oxygen.
So, the number of moles of oxygen, O2, produced is:
Number of moles of oxygen = (Number of moles of ozone) * (3/2)
Number of moles of oxygen = 0.10 mol * (3/2)
Number of moles of oxygen = 0.15 mol
Step 4: Substitute the values into the ideal gas law equation.
We have:
P * V = n * R * T
Substituting the values:
P * (2.45 L) = (0.15 mol) * (0.0821 L·atm/mol·K) * (298.15 K)
Step 5: Solve for pressure (P)
P = [(0.15 mol) * (0.0821 L·atm/mol·K) * (298.15 K)] / (2.45 L)
P ≈ 2.38 atm
So, the pressure inside the flask, once the reaction is complete, is approximately 2.38 atmospheres.