Determining Limiting and Excess Reactants in Chemical Reactions
How do we determine the limiting and excess reactants in a chemical reaction?
In a chemical reaction, if 4.21L of NH3 at 27°C and 1.02 atm is combined with 5.35L of HCl at 26°C and 0.998 atm, what mass of NH4Cl will be produced? Which gas is the limiting reactant? Which gas is the excess reactant?
Identifying the Limiting and Excess Reactants
To determine the mass of NH4Cl produced, the first step is to identify the limiting reactant and the excess reactant.
Once the limiting reactant is identified, the stoichiometry of the balanced chemical equation can be used to calculate the mass of NH4Cl produced. In this case, the balanced chemical equation is:
2NH3 + HCl -> NH4Cl
We can start by converting the given volumes of NH3 and HCl to moles using the ideal gas law:
Moles = (pressure * volume) / (gas constant * temperature)
After calculating the moles of NH3 and HCl, we compare their stoichiometric ratios in the balanced chemical equation to determine the limiting reactant. The reactant present in the lesser stoichiometric amount will be the limiting reactant, while the other will be the excess reactant.
Once the limiting reactant is identified, we can calculate the theoretical yield of NH4Cl and convert it to mass using the molar mass of NH4Cl.
Detailed Explanation
In this scenario, we are given the volumes, temperatures, and pressures of NH3 and HCl gases that are reacting to form NH4Cl. The first step is to use the ideal gas law to convert the volumes of gases to moles. This allows us to compare the amount of each gas in the reaction.
The balanced chemical equation shows that 2 moles of NH3 react with 1 mole of HCl to produce 1 mole of NH4Cl. Therefore, we need to determine which gas is present in the limiting amount to calculate the maximum amount of NH4Cl that can be produced.
By comparing the moles of NH3 and HCl, we can identify the limiting reactant. The limiting reactant is the one that is completely consumed in the reaction, while the excess reactant is left over after the limiting reactant is used up.
Once the limiting reactant is determined, we can calculate the theoretical yield of NH4Cl based on the stoichiometry of the reaction. This allows us to find the mass of NH4Cl produced from the limiting reactant.
Understanding the concept of limiting and excess reactants is crucial in chemistry as it helps us optimize reactions for maximum yield and efficiency. By identifying the limiting reactant, we can ensure that all reactants are used efficiently without any wastage.