given the following equation N2(g)+3H2(g)=2NH3(g) determine to one decimal place the molar mass of each substance and express each mass in grams per mole
The Correct Answer and Explanation is:
To determine the molar mass of each substance in the equation:
Balanced equation: N2(g)+3H2(g)→2NH3(g)\text{N}_2(g) + 3\text{H}_2(g) \rightarrow 2\text{NH}_3(g)
We calculate the molar mass using the atomic masses from the periodic table:
- Nitrogen (N) = 14.0 g/mol
- Hydrogen (H) = 1.0 g/mol
Molar Masses:
- N₂ (Nitrogen gas):
2×14.0=28.0 g/mol2 \times 14.0 = 28.0 \, \text{g/mol} - H₂ (Hydrogen gas):
2×1.0=2.0 g/mol2 \times 1.0 = 2.0 \, \text{g/mol} - NH₃ (Ammonia):
1×14.0+3×1.0=17.0 g/mol1 \times 14.0 + 3 \times 1.0 = 17.0 \, \text{g/mol}
Final Answers (to one decimal place):
- N₂ = 28.0 g/mol
- H₂ = 2.0 g/mol
- NH₃ = 17.0 g/mol
To calculate the molar mass of a chemical compound, we add up the atomic masses of all atoms in one molecule of that substance. The atomic mass values are found on the periodic table and are expressed in grams per mole (g/mol), which means the mass of one mole of that substance.
In the balanced chemical equation: N2(g)+3H2(g)→2NH3(g)\text{N}_2(g) + 3\text{H}_2(g) \rightarrow 2\text{NH}_3(g)
Each substance involved is a molecule, so we calculate the mass of each based on its molecular structure:
- N₂ (Nitrogen gas) consists of two nitrogen atoms. Since each nitrogen atom has an atomic mass of 14.0 g/mol, the molar mass of N₂ is 2×14.0=28.02 \times 14.0 = 28.0 g/mol.
- H₂ (Hydrogen gas) consists of two hydrogen atoms. With each hydrogen atom having a mass of 1.0 g/mol, the molar mass of H₂ is 2×1.0=2.02 \times 1.0 = 2.0 g/mol.
- NH₃ (Ammonia) has one nitrogen and three hydrogen atoms. Its molar mass is 14.0+(3×1.0)=17.014.0 + (3 \times 1.0) = 17.0 g/mol.
These molar masses are essential for stoichiometric calculations in chemistry. For instance, they help chemists determine how much of each reactant is needed or how much product will form in a chemical reaction. Since the equation is already balanced, the molar ratio directly relates to the molar masses in grams for each compound. This supports accurate conversions between mass and moles in real-world chemical applications.
