2. Methane (CH4), ammonia (NH3), and oxygen (O2) can react to form hydrogen cyanide (HCN) and water according to this equation:
CH4 + NH3 + O2 HCN + H2O
You have 8 g of methane and 10 g of ammonia in excess oxygen. Answer the following questions:
• What is the balanced equation for this reaction?
• Which reagent is limiting? Explain why.
• How many grams of hydrogen cyanide will be formed? Show your work
To answer these questions, we need to follow a step-by-step process:
1. Balanced Equation:
To balance the equation, we need to ensure that there is an equal number of each atom on both sides. The balanced equation for the given reaction is as follows:
CH4 + 2NH3 + 3O2 -> HCN + 3H2O
2. Limiting Reagent:
To determine the limiting reagent, we compare the moles of each reactant to the stoichiometric ratio in the balanced equation. The reactant that produces the fewest moles of the product is the limiting reagent.
First, we need to determine the moles of each reactant. We can use the molar mass of each compound to convert grams to moles.
Molar mass of CH4 (methane) = 12.01 + 4(1.01) = 16.05 g/mol
Moles of CH4 = mass / molar mass = 8 g / 16.05 g/mol = 0.498 mol
Molar mass of NH3 (ammonia) = 14.01 + 3(1.01) = 17.03 g/mol
Moles of NH3 = mass / molar mass = 10 g / 17.03 g/mol = 0.587 mol
Since the balanced equation shows 1 mole of CH4 reacting with 2 moles of NH3, we need to compare the ratio of moles between CH4 and NH3.
Moles of CH4 / Stoichiometric coefficient of CH4 = 0.498 mol / 1 = 0.498 mol
Moles of NH3 / Stoichiometric coefficient of NH3 = 0.587 mol / 2 = 0.2935 mol
From the calculations, we see that the mole ratio of CH4:NH3 is approximately 1.7:1. This means CH4 is present in excess, and NH3 is limiting, as it will be completely used up first.
3. Grams of Hydrogen Cyanide (HCN):
To determine the amount of HCN formed, we need to use the stoichiometry of the balanced equation. From the balanced equation, we can see that the stoichiometric coefficient of HCN is 1. This means that 1 mol of NH3 reacts to form 1 mol of HCN.
Moles of HCN = Moles of NH3 = 0.2935 mol
To calculate the mass, we multiply the moles of HCN by its molar mass.
Molar mass of HCN (hydrogen cyanide) = 1.01 + 12.01 + 14.01 = 27.03 g/mol
Mass of HCN = Moles of HCN * Molar mass of HCN
= 0.2935 mol * 27.03 g/mol
= 7.91 g
Therefore, approximately 7.91 grams of hydrogen cyanide will be formed.