Final answer:
Approximately 22.32 grams of NH3 are required to react with 21 grams of CH3OH, using the molar mass of NH3 and CH3OH and the stoichiometric ratios from the balanced chemical equation.
Step-by-step explanation:
To determine how much NH3 is needed to react exactly with 21 grams of CH3OH, we need to use stoichiometry. First, we need the molecular weights of NH3 and CH3OH to convert grams to moles. The molecular weight of NH3 (ammonia) is about 17.03 g/mol, and the molecular weight of CH3OH (methanol) is approximately 32.04 g/mol.
Using the provided molecular weights, you can calculate the moles of CH3OH by dividing the mass by the molecular weight:
moles of CH3OH = 21 g / 32.04 g/mol ≈ 0.655 moles
The balanced chemical equation 2 NH3 + CH3OH → products tells us that 1 mole of CH3OH reacts with 2 moles of NH3. Hence, for 0.655 moles of CH3OH, we need:
0.655 moles of CH3OH x 2 moles of NH3 / 1 mole of CH3OH = 1.31 moles of NH3
To find the mass of NH3 required, multiply the moles of NH3 needed by its molecular weight:
mass of NH3 = 1.31 moles x 17.03 g/mol ≈ 22.32 grams
Therefore, approximately 22.32 grams of NH3 are required to react with 21 grams of CH3OH.