If 2.5 L N2 reacts with 7 L H2, what is the theoretical yield (in liters) of NH3? Assume that the volumes of reactants and products are measured at the same temperature and pressure.
This is a limiting reagent problem. I know that because a value is given for BOTH reactants. In this case, where all of the materials are gases, one may take a shortcut and use volumes as moles.
Using the coefficients in the balanced equation, convert 2.5 L N2 to L NH3. Do the same for 7.0 L H2. The answers will not be the same; the correct answer in limiting reagent problems is ALWAYS the smaller value. The answer you obtain will be the theoretical yield.
To determine the theoretical yield of NH3, you need to use the balanced chemical equation for the reaction between N2 and H2 to form NH3.
The balanced chemical equation for the reaction is:
N2 + 3H2 -> 2NH3
From the equation, you can see that 1 mole of N2 reacts with 3 moles of H2 to produce 2 moles of NH3.
To find the number of moles of N2, you can use the ideal gas law:
PV = nRT
Given that the volume of N2 is 2.5 L, you can assume the pressure and temperature remain constant. The value of R is the ideal gas constant, and T is temperature in Kelvin.
Next, convert the volume of N2 to moles using the ideal gas law equation:
n = PV / RT
Next, find the number of moles of H2 using the same process. Given that the volume of H2 is 7 L, you can convert this to moles using the ideal gas law equation.
From the balanced chemical equation, you know that the stoichiometric ratio between N2 and NH3 is 1:2. This means that for every 1 mole of N2, you produce 2 moles of NH3.
Using this information, calculate the number of moles of NH3 that can be produced by multiplying the number of moles of N2 by the stoichiometric ratio.
Finally, convert the moles of NH3 to liters by using the ideal gas law equation in reverse:
V = nRT / P
Where:
V = volume in liters
n = number of moles
R = ideal gas constant
T = temperature in Kelvin
P = pressure
Substitute the values you have calculated into the equation, and you will have the theoretical yield of NH3 in liters.