Questions: Stoichiometry Calculating and using the molar mass of diatomic elements A chemist determines by measurements that 0.0850 moles of nitrogen gas participate in a chemical reaction. Calculate the mass of nitrogen gas that participates. Be sure your answer has the correct number of significant digits. g × 10

Solution Steps

• Nitrogen gas ($N_2$) is diatomic, meaning each molecule consists of two nitrogen atoms.
• The atomic mass of nitrogen ($N$) is approximately 14.01 g/mol.
• Therefore, the molar mass of nitrogen gas ($N_2$) is: $$2 \times 14.01 \, \text{g/mol} = 28.02 \, \text{g/mol}$$

• Use the formula: $$\text{mass} = \text{moles} \times \text{molar mass}$$
• Given that the number of moles of nitrogen gas is 0.0850 moles: $$\text{mass} = 0.0850 \, \text{moles} \times 28.02 \, \text{g/mol}$$

• Calculate the mass: $$\text{mass} = 0.0850 \times 28.02 = 2.3817 \, \text{g}$$

• The given number of moles (0.0850) has three significant digits.
• Therefore, the mass should also be reported with three significant digits: $$\text{mass} \approx 2.38 \, \text{g}$$

Final Answer