a 2L container is charged with 2atm of O2 at 298 Kelvin.
Ch4(g) + 2O2(g) --> CO2(g) + 2H20(g)
calculate the partial pressure of methane needed to react completely with the O2 in the vessel. What is the total pressure after the reaction is complete if the temperature increased to 750 Celcius?
Responses
AP chem - DrBob222, Saturday, April 11, 2009 at 11:54pm
Use PV = nRT
You know P, V, R, and T, calculate n for oxygen.
That allows you to calculate CH4 moles and from there moles CO2 and moles H2O.
Then calculate total P from new conditions for PV = nRT.
NEW:
once I have calculated the number of moles, how do i calculate the partial pressure of methane needed to completely react with O2? is that the number of moles?
I have you need .0817 moles of methane but i don't know if this is the same as partial pressure
Answered below.
To calculate the partial pressure of methane needed to completely react with O2, you cannot directly use the number of moles of methane. The partial pressure is the pressure exerted by a particular gas in a mixture of gases. In this case, you need to consider the stoichiometry of the reaction.
The balanced equation for the reaction is: CH4(g) + 2O2(g) --> CO2(g) + 2H2O(g)
From the balanced equation, you can see that 1 mole of CH4 reacts with 2 moles of O2. Therefore, to completely react with the 2 moles of O2 in the container, you would need 0.5 moles of CH4.
To calculate the partial pressure of methane, you need to use the ideal gas law equation, PV = nRT.
First, calculate the number of moles of methane (CH4) using the ideal gas law equation and the initial conditions given: P = 2 atm, V = 2 L, T = 298 K.
PV = nRT
(2 atm)(2 L) = n(CH4)(0.0821 L.atm/mol.K)(298 K)
n(CH4) = (4 L.atm) / (0.0821 L.atm/mol.K)(298 K)
Once you calculate the number of moles of methane (CH4), you can then use this information to calculate the partial pressure. The partial pressure is the pressure exerted by a gas in a mixture and is calculated using the formula:
Partial Pressure = (moles of the gas) x (total pressure of the system)
In this case, the total pressure of the system is 2 atm (given in the question). So, you can calculate the partial pressure of methane by multiplying the moles of methane (0.0817 mol) by the total pressure (2 atm).
Partial Pressure of Methane = (0.0817 mol) x (2 atm) = 0.1634 atm
To calculate the total pressure after the reaction is complete at a temperature of 750 degrees Celsius, you would use the same ideal gas law equation, but with the new temperature.
PV = nRT
P(2 L) = n(CH4)(0.0821 L.atm/mol.K)(1023 K)
Rearrange the equation to solve for P:
P = (n(CH4) x 0.0821 L.atm/mol.K x 1023 K) / (2 L)
Plug in the value of n(CH4) (0.5 moles) and solve for P to get the total pressure after the reaction.
I hope this explanation helps you understand how to calculate the partial pressure of methane and the total pressure after the reaction.